Microwave-assisted extraction (MAE) was applied for the extraction of astaxanthin from Haematococcus pluvialis and response surface methodology (RSM) was used to optimize extraction parameters to the content of astaxanthin. Four independent variables such as microwave power (W), extraction time (sec), solvent volume (mL), and the number of extraction were optimized in this paper. The optimal conditions were determined and tri-dimensional response surfaces were plotted from the mathematical models. The F-test and p-value indicated that microwave power, extraction time, the number of extraction, and their quadratic had a highly significant effect on the response value (p0.01), then the solvent volume and the interaction effects of microwave power and the number of extraction also displayed significant effect (p0.05). Considering the extraction efficiency, the optimized conditions of MAE were as follows: microwave power was 141W, extraction time 83 sec, solvent volume 9.8mL, the number of extraction four times. About 5943.02g astaxanthin was extracted from Haematococcus pluvialis the dried powders (100mg) under the optimal conditions, and it close to the predicted contents (592g). The antioxidant activities of the extracts obtained under optimal conditions were analyzed, and the results showed that the extracts presented strong ability of inhibiting the peroxidantion of linoleic acid, exhibited strong radical-scavenging properties against the DPPH, as well as strong reducing power.