A new analysis program, DPSⅠ, for simple positron annihilation lifetime spectrum which only reflects to the properties of the interior of the specimen is designed in C++ language. Based on Metropolis rule, the algorithm of DPS I is a kind of advanced simulated annealing algorithm with remembrance function and part-scope search. Generally, DPSⅠ may exactly give integral optimal results after inversion.And also, approximate integral optimal results can be acquired if the comparative intensity is small or the overlapped range is serious. DPSⅠ has laid the foundation for designing analysis program of positron annihilation lifetime spectrum from experiments.