The invention discloses an operation method of a grid-connected microgrid under differential power supply price, comprising the following steps: (1) determining the current electricity price at time t, and then calculating whether a combined cooling heating and power system can generate profits; (2) comparing the sum of the load demand and the cooling heating and power demand with the photovoltaicpower generation output when the combined cooling heating and power system cannot generate profits, if the sum is more than or equal to the output, discharging from energy storage batteries or purchasing electricity from large power grids; if the sum is less than the output, charging the energy storage batteries or selling electricity to the large power grids; and (3) comparing the load demand with the sum of the photovoltaic power generation output and the combined cooling heating and power when the combined cooling heating and power system can generate profits, and adopting the same principle as the step (2). The operation method of the present invention analyzes the load convergence characteristics of the grid-connected points to obtain the output strategy and the state change path under different scenarios of various power supplies, and establishes an optimized operation model based on the analysis, analyzes the output characteristics of the grid-connected microgrid, and lays thefoundation for planning and designing the grid-connected microgrid.