With three Paeonia rockii varieties (‘Xiangyabai’, ‘Meirenmian’, ‘Zijinguan’) single and semidouble pollens as materials, the optimal medium for pollens of Paeonia rockii was determined. We observed and studied the ultrastructure and physiological and biochemical characteristics of pollen, explored the relationship between the ultrastructure of single and semi-double pollens and pollen germination rate, and the relationship between material metabolism and pollen germination rate. The results show that: (1) the most suitable culture medium for the germination of P. rockii powder is: 100 g·L^-1 sucrose+0.15 g·L^-1 boric acid+10 g·L^-1 agar. (2) Pollen fullness is the main reason that affects pollen germination. (3) The germination rate of single valve pollen of three P. rockii varieties was significantly higher than that of semi-valve pollen. (4) The soluble protein content of ‘Xiangyabai’, ‘Meirenmian’ and ‘Zijinguan’ crown pollen was higher than that of semi-valve pollen, but the MDA content and three protective enzymes (CAT, SOD, POD) were lower than that of semi-valve pollen. It is believed that protein loss and accumulation of MDA, CAT, SOD and POD in pollen may be one of the physiological reasons for the low germination rate of semi-heavy valve P. rockii powder.