In order to explore the impacts of strain rate on the intensity and deformation of Shanghai andesite, six different strain rates (from 1×10-5s-5 to 1s-5) were used in the experiments; three specimen sizes were selected (D= 38mm, L= 38mm; D= 38mm, L= 76mm; D= 58mm, L= 116mm) to study the effects of specimen sizes; the computer controlled servo rigid triaxial testing machine was used for specimen uniaxial compression tests. The results showed that: There was a critical strain rate εcr, when strain rate was lower than εcr, rock peak stress and ultimate strain increased as the strain rate increased, otherwise, it declined; The aspect ratio had certain influences on the critical strain rate εcr, if the aspect ratio of the specimen was doubled, then the value of εcr increased an order of magnitude; when the diameter of the specimen was constant, with the increase of the aspect ratio, there was an obvious increase in the peak stress of rock, however, the failure strain decreased significantly; when the aspect ratio was fixed, as the increase in size, peak stress decreased obviously, while the impact on the ultimate size of the strain was small.