This paper proposes a new population-based heuristic algorithm called Phasmatodea (stick insect) Population Evolution (PPE) algorithm. The implementation of the algorithm is inspired by the evolutionary characteristics of stick insect population. Stick insects will change their shape to adapt to the surrounding environment, and stick insect populations will also evolve as the environment changes. This paper implements the PPE algorithm based on the relevant characteristics of the stick insect and the population model. The PPE algorithm is compared with the classic and newer algorithms on 30 benchmark functions. The results show that the proposed algorithm has strong competitiveness. Then this paper tries to apply the proposed algorithm to the downlink power allocation problem in the fifth-Generation (5G) heterogeneous network, and has achieved certain results.