A large-scale research on the affective diathesis of college students in China is a significant though challenging endeavor. Based upon the theory of affective diathesis and thoughts of developmental affection with classified thoughts, current study developed an original investigative tool with solid reliability and validity—“Questionnaire on College Students’ Affective Diathesis”. This instrument dealt with the complexities in affect measurement and is of great theoretical and practical significance. The questionnaire was used to investigate college students’ affect development on thirty-three different kinds of affects, including patriotism, responsibility, integrity, credibility, dedication, fairness, public benefit; curiosity, exploration, self-confidence, achievements, learning happiness, major interest; intimacy, cooperation, forgiveness, emotionally appealing, gratefulness, care; self-improvement, self-reliance, self-esteem, cherish, happiness, optimism; aesthetic for nature, aesthetic for humanity, aesthetic for science, aesthetic for deportment; emotional understanding ability, emotional expression ability, emotional control of oneself, emotional control of others. They belong to six categories (moral affection, rational affection, interpersonal affection, life affection, aesthetic affection and emotional intelligence) evolving from the identity layer of affection and the operational layer of affection. The questionnaire was administered to 11982 college students, including vocational college students and university students. The geological regions encompassed well-developed, developing and less-developed regions in China involving 100 colleges and universities of 14 major cities (Beijing, Shanghai, Guangzhou, Nanjing, Changchun, Zhengzhou, Xi'an, Wuhan, Xining, Lanzhou, Guiyang, Nanning, Haikou, and Kunming). The results showed: (1) The questionnaire meets the criteria of an effective measurement tool and serves as an original investigative tool for affective diathesis of college students. (2) The college students’ affective diathesis has a multilevel structure. On the whole, the affective diathesis of college students in China is positive. The developmental level of moral affection and life affection is relatively higher, and the developmental level of interpersonal affection, aesthetic affection, rational affection and emotional intelligence were relatively lower. Affections of integrity, public benefit, dedication, exploration, learning happiness, self-confidence, forgiveness, intimacy, emotionally appealing, aesthetic for humanity, aesthetic for science and ability of emotional expression were still in urgent need of improvement. (3) A structural difference mainly existed between males and females. Females scored higher in intimacy, emotionally appealing and self-esteem, but males performed better on integrity, curiosity, exploration, self-confidence, aesthetic for science and emotional expression. (4) Those who received awards, reported achieving higher academic performance, or experienced no negative life events showed higher level of affective diathesis, especially reflected in self-confidence, achievements, learning happiness, self-improvement, happiness etc. (5) The factors affecting the affective diathesis development of the college students mainly derived from four aspects: individuals, families, schools and society. Strong interpersonal relationship, more public awareness, sound moral values, high self-expectations, democratic family education style et al. all had positive effects on college students’ affective diathesis. This investigation equips educators with abundant first-hand information on how to improve the affective diathesis of college students as well as for academics on the theoretical implications for affective diathesis research.