Abstract: Abstract: Poria cocos is a traditional Chinese herbal medicine. It generally takes almost 7 days to be dried by traditional natural drying, and it is sensitive to microbial spoilage during drying. Poria cocos blocks (15 mm×15 mm×15 mm) are easily broken at the traditional hot air drying, such as oven drying. There are many drying methods, but we don’t know how to choose the method quickly. The knowledge of different drying mechanism is necessary for heat and moisture transportation, energy savings and quality of product. To study the drying characteristics of poria cocos, overcom the drawbacks of poria cocos blocks which is easily broken and surface cracking after drying, improve the quality of dried poria cocos and shorten its drying time, the nature drying, oven drying ,air impingement drying, pulsed vacuum drying approaches were applied to poria cocos drying. The Weibull distribution model was applied to the drying process under different drying methods and the results were analyzed. Combined with the GB-4857.5 T–1992《Droping test method》and《Pharmacopoeia of People’s Republic of China》, the broken rate and extractum of poria cocos at different drying conditions were tested. The moisture effective diffusivity velocity and the activation energy were also calculated based on the scale parameter and shape parameter, and compared with Fick’s second law. A comprehensive evaluation was also carried out for kinds of artificial drying methods based on the utilization rate of energy consumption, scale parameter, broken rate, extractum. The main results are as following: 1)four drying methods drying process all occurred in the falling rate period without constant speed stage, but oven drying and pulsed vacuum drying had the up-stage at the starting; 2) Weibull function can fit the drying curve of different methods accurately. Scale parameter decreased with the increasing temperature and air velocities. The shape parameter was related to the drying method, the shape parameter of oven drying and vacuum drying was higher than 1,and the air impingement drying’s shape parameter was lower than 1; 3) the moisture effective diffusivity velocity and the activation energy were calculated based on the Weibull function, it can overcome the defects that the Fick's second law only was applied to the falling rate drying; The moisture effective diffusivity of poria cocos was 3.90×10-9-20.40×10-9 m2/s; the activation energy was 29.45-40.09 kJ/mol, but there were differences among different drying methods; 4) the broken rate of poria cocos blocks exhibited significant difference for different drying methods, the broken rate of nature drying and vacuum drying was lower than 5.00%; At the range of testing parameters, temperature and air velocities didn’t have significantly impact on the broken rate, The average was 62.68%; The broken rate increased with the rising temperature at oven drying; and 5) the extractum of poria cocos dried by pulsed vacuum method was most than others, and it ranged from 4.54% to 4.75%. Comprehensive evaluation results showed that the best drying method is pulsed vacuum drying. The results provide a reference for the application of Weibull distribution on poria cocos drying and help people gain the best drying method.