Objective To investigate the differences of the working memory tasks' performance between the patients with no neurological syphilis disease and the health controls (HC).Methods 2-back test of N-back task paradigm were applied to measure the performances of working memory.A total of 30 patients with syphilis disease were compared with 35 gender-,age-,years of education-matched healthy persons,then compared the accurate rate and reaction time on the tasks between the two groups.Results Participants with anxiety or depression had to be excluded.The results showed that patients impaired on working memory task.The accurate rate and reaction time of the working memory of the patients was worse than that of the healthy persons ((65.31 ± 8.78) ％ vs (71.00 ±9.64)％ ;(1521.14 ±290.57)ms vs (1296.08 ±253.20)ms respectively) (t=-2.472,P=0.016;t=3.337,P =0.001 respectively).The study indicated the reaction time of the working memory for the patients was negative correlation to the age of final diagnosis (r =-0.362,P =0.049).Conclusion The patients with no neurological syphilis disease show impairment on working memory.This probably because treponema pallidum injures the central nervous system.