This paper studies on the droop control of non-simultaneously cut-in inverters in islanded microgrid, which is aimed at achieving balanced power between inverters and voltage (frequency and amplitude) without static error by no communication. Firstly, this paper indicates an issue with non-simultaneously cut-in inverters based on current droop control scheme, i.e., unable to ensure balanced power and voltage without static error at the same time. Next, in order to ensure balanced power between inverters, a general rule is derived. And then an improved droop control scheme based on the rule is proposed. This scheme adopts a specific correction method of no-load voltage frequency and amplitude, which can control the voltage to be without static error and the output power of inverters to be balanced without communication. The conclusions of this paper have been verified by the final simulations, which demonstrate that the proposed droop control scheme reaches the expected effect and solves the issue with non-simultaneously cut-in inverters.