The invention relates to a cement soil plane strain tester; a shell (6) is connected between an upper and a lower covers (5 and 5a) to form a pressure chamber; the upper cover (5) is provided with a sliding top rod (4) connected with a piston rod of a hydraulic cylinder (1); the lower end of the top rod (4) is connected with a loading plate (7); a sample side pressure plate (10) is arranged between the upper loading plate (7) and a lower loading plate (7a); the cement soil plane strain tester is characterized in that a. the pressure chamber is internally provided with a counter-force frame (23); b. one end of the counter-force frame is provided with an adjusting screw rod (22) which is contacted with the sample side pressure plate (10); c. the upper and the lower loading plates are respectively provided with drain pipes (8 and 18) which are connected with flow meters (11 and 26); and d. the piston rod is provided with sensors (2 and 3), and the counter-force frame is internally provided with a sensor (14). The cement soil plane strain tester has the advantages that the mechanics characteristics of cement soil plane strain can be tested in a room, the problems of regulation and control of principal stress and accuracy thereof can be solved by using the adjusting screw rod to adjust the contact between the pressure plate along the direction of the principal stress and a sample, and the problem of contact between the sample and the pressure plate after consolidation and deformation of the principal stress can be also solved.