Abstract: This essay focuses on studying optimal investment policies of an insurer after adding the real estate investment factorWe assume the insurer's risk process follows the classic CramerLundeberg model, and the insurer can invest their fund into cash market and two risk markets, which are bond, stock and real estate marketsUnder the constraints of no short selling and no borrowing, based on the MeanVariance model, this essay uses the stochastic linearquadratic (LQ) control theory as calculation method to derive the optimal investment policies and efficient frontierAccording to the results, the real estate optimal investment amount not only shows nonsimple linear relationship with the company's initial capital, but it also shows a series of complex relationships with the market premium of real estate and with unpredicted shocks