People usually read for information. A study shows that readers usually do search reading in order to find the relevant information related to their work or study. According to the requirement of authenticity that testing forms should be in line with students’ real life activities, search reading should be included in CET(College English Test), which is one the most important tests for college students in China. How to realize a better validity of search reading in CET? On the one hand, it is widely believed that long passages test different reading abilities from short passages; on the other hand, it is better to test search reading through long passages due to the nature of search reading. Therefore, a reading test should include both long passages and short passages. The main purpose of this research is to find out the proper ratio of long passages to short passages in a reading test in a paper, which can best test the participants’ reading proficiency. Through the correlation analysis of the final exam and different combinations of one long passage and different number of short passages, the author found out that the proper ratio is 1:2.