The XSL algorithm is a method for solving systems of multivariate polynomial equations based on the linearization method on GF（2）

and the T ’ method is the final stage of the XSL algorithm before linearization.Through analysis revealed that the T ’ algorithm can not achieve its desired end condition Free = T or Free=T-1.In orde to solve the problem

a real end condition and two variable selection principle was proposed for T′ algorithm.Based on probabilistic algorithms and variable values greater probability estimation method to improve performance of the original T ’algorithm.The results show that the improved T ’algorithm can simplify the equations.