Abstract: Addition and subtraction word problems refer to a type of mathematical word problems that can be solved by applying addition and subtraction. They can be mainly classified into three categories: combine, change and compare. There are four types of methods to investigate the mental processes: solving problem, recalling and constructing problems, building simulation model of computer, and recording eye-movement. Previous research found that the mental processes could be significantly affected by these factors: semantic type, age, phrase and sentence, narrating format, context personalization, the structure of problem text, number size, the type of unknown set and strategies to solve problems. Researchers mainly proposed two theoretical explanations for the mental processes: mathematical knowledge applying model and language comprehension model

Key words: addition and subtraction word problems, arithmetic word problem, problem solving, mathematical cognition, mathematical education