Objective To study the means of humidity control for long-term sealed storage composite packages. Methods The primary influencing factors on relative humidity of sealed packages were analyzed. The moisture barrier structure design of sealed composite packages, desiccant selection and dosage calculation formula were studied, and the drying process parameters of typical desiccant were analyzed. Results The methods and key points in moisture barrier structure design were proposed. The dosage calculation formula of desiccant was optimized. Conclusion According to the test results, the optimal drying process temperature(140 ~ 150 ℃ ) and time(8 ~ 9 h) of silica gel desiccant were acquired.