A new heuristic method for solving multi-period economic dispatch for thermal power plants was proposed.The dynamic programming method was applied to obtain the optimal start and stop status of each unit which was to be started and the corresponding start and stop cost which satisfied the cramping constraint under system load condition

thus to put the unit with the highest efficiency into service.Then

for the thermal power units whose start and stop status was certain

the optimal economy distribution that satisfying the system constraint was conducted.The simulation results showed that

this new heuristic approach overcame the problems appeared in priority list method

like difficult to obtain the unit start and stop cost

insufficient influence of cramping constraint on unit priority.It is practicable and effective.