Abstract： Objective To validate the feasibility of the self developed digit critical fuse frequency apparatus (DCFFA) and suggest more objective, accurate and reliable measurement in fatigue evaluation. Methods Twenty-one male students were selected as subjects for the test where a 7-seg digit ("0" to "9") was randomly generated by DCFFA with odd frequency from 25-49 Hz. Subjects responded the digit by key pressing and the reaction time (RT) and accuracy of responding were recorded. Subject's critical fuse frequency (CFF) values were partitioned by accuracy (range from ＞60%, 40%-60% and ＜40%) as high CFF, CFF and low CFF group respectively. RT and accuracy were then analyzed by descriptive statistics, equality of variances and paired-sample t test. Results When the applied frequency was respectively lower or higher than CFF, the recorded RT was (3.56±1.92) sor (2.99±1.91) s. And when it was set around CFF, the RT [(4.23±2.11) s] was significantly higher than that in the frequency above CFF (P＜0.01). Conclusions The validation proved that DCFFA could objectively detect CFF with accurate and reliable measurement.