The purposes of this study were: (1) to investigate the relationship between latent trait theory (LTT) and classical test theory (CTT), and (2) to evaluate the efficiency of latent trait theory applied to the adaptive testing. Computer simulation was used in this study. The response patterns of the "examinee" were first generated, and the procedures of adaptive testing were simulated, supposing θ known and θ unknown. The testing paths of each examinee were traced, recorded, and analyzed. The results were summarized as follows: (1) The a, b, θ parameters in LTT were highly correlated with r(subscript bla), P, and obtained score in CTT respectively. (2) whenθwas supposed to be known, the adaptive testing paths could be classified into three patterns according to b parameter in testing path. These three paths patterns belonged to examinees of high, middle and low ability level respectively. Apparantly, the paths were formulated by matching examinee´s ability and item difficulty. when less then 50% of items in the pool were taken, the efficiency of measurement was the same as when all items in the pool were taken. (3) whenθwas suppsed not to be known, the adaptive testing paths could be classified into two patterns according to a paramter, into three patterns according to b parameter, and into four patterns according to c parameter in path. The Paths were also formulated by matching examinee´s ability and item difficulty. However, the efficiency of measurement was not stable. Based on the results of this study, the conclusions were drawn: (1) The basic concepts of LTT and CTT were similar and consistent. (2) It was practicable to apply LTT to adaptive testing, however the techniques of estimatingθshould be improved furthur.