Abstract: Feed-in tariff and renewable portfolio standard are the most popular regulatory methods in renewable energy industry. By establishing a two-stage model where monopoly firm first chooses R&D input and then the quantity of energy, this paper compares the different effects of two regulatory policies: feed-in tariff and renewable portfolio standard. The results show that FIT is more effective than RPS at increasing the quantity of renewable energy (installed capacity) and stimulating R&D input based on cost saving; And RPS policy is more effective at reducing carbon emissions and improving consumer surplus. Apart from existing findings, we cannot obtain the accurate conclusion that whose social welfare is better under the two policies. It depends on the level of negative externality.