Abstract: This paper investigates the formation flying around a displaced orbit.The equation for relative motion is derived. Since the displacement betweentwo different solar sails is very small compared with the displacement fromthe sails to the sun, the equation of motion is linearized around thenominal displaced solar orbit to obtain a linear equation. Based onthe linear equation, three formation control strategies are discussed,including the passive control strategy. This strategy has the advantagesof simplicity and large stable region. Simulations based on thenonlinear equaiton are given. The results show that strategies canrealize the formation around the displaced solar orbit.