Objective: To explore the impact of media multitasking behavior on the depth of information processing by analyzing the relationship between media multitasking behavior and academic performance of college freshmen in terms of ecological validity. Method: A total of 178 college freshmen were selected, and the media multitasking index was measured using a media usage questionnaire. The heavy media multitasking behavior group (HMM) and light media multitasking behavior group (LMM) were selected, and the differences in demographic information, mobile phone usage, and academic performance in the college entrance examination, professional courses, and public courses between the HMM and LMM groups were analyzed and compared. Result: There was no significant difference in demographic information, mobile phone usage, and college entrance examination scores between the HMM and LMM groups, as well as subjective and objective scores in professional courses. However, there was a significant difference in objective scores in public courses (P < 0.05), and there was a marginal difference in subjective scores in public courses, all of which were lower in the HMM group than in the LMM group. Long term media multitasking behavior can weaken individuals’ ability to deeply process information and affect the academic performance of college students. Innovation: There has been limited research on the impact of media multitasking behavior on information processing in the past. This study starts from the perspective of ecological validity, analyzes the differences in the impact of media multitasking behavior on the academic performance of college freshmen in professional and public courses, and concludes the relationship between media multitasking behavior and information processing. That is, the more media multitasking behavior, the shallower the individual’s information processing level.