The research work of hardness on evolutionary algorithm is an important branch of evolutionary computation.It aims to study the relationship between the performance of evolutionary algorithm and the characters of the optimization problem.And

the goal of the hardness research is estimating the performance of an evolutionary algorithm deployed in one optimization problem by using limited information.This paper summarizes six kinds of hardness theories on evolutionary algorithm

such as fitness-distance correlation model

fitness landscape methods

landscape state machine

optimal contraction theorem

epistasis methods

etc.and eight hardness indicators with them.Furthermore

this paper discusses the advantages and disadvantages of these methods

and prospects the trends of this research field.