Abstract: As a nondestructive testing technique, fluorescent penetrant inspection has been widely applied in titanium alloy casting defect detection. However, as one of the key parameters in fluorescent penetrant inspection, the influence of development time on inspection results has not been thoroughly studied. Using titanium alloy castings as research objects, this study deeply investigated the impact of development time on fluorescent penetrant inspection effectiveness. First, under the premise that all parameters of the fluorescent penetrant inspection system met standard requirements, a control variable method was employed to systematically study development time´s influence on inspection results. Then, development time was varied to observe and record changes in casting inspection results. Through experimental data analysis, optimal development time was determined, thereby improving the accuracy of titanium alloy casting fluorescent penetrant inspection.