Effects of three types of tester in maize which evaluated general combining ability(GCA) of the testing-iine were strdied comparatively.The results indicated that aester classes were an inportant reference inder for screeing superiou tester when GCA of yield was tesed.The syn-thetic variety was tested.The synthetic variety was a sort of good teser and generally could be used alone as tester.Superior tester could be obtained from the serious choice of interlinear hybrid and inbreed.Generally,the esrious chice for tester wasn't necessary when the GCA of the agricultural characters was tested.