Crack propagation under tensile strain in samples with pre-deformation is simulated using phase field crystal(PFC) method. It shows that crack of sample without pre-deformation, under tensile strain, begins to crack due to strain concentration as strain reaches a critical value. For pre-deformed samples, crack starts to propagate at a less critical strain value, and the larger the pre-deformation, the faster and more obvious the crack growth. For samples with pre-deformation during early process of crack propagation, growth characteristics of expansion-turning direction-expansion are presented. The essence is that crack growth is extended by atomic bond alternative fracture in directions[√3,1] and[√3,-1] of primary and secondary atomic arrangement direction, which leads to zigzag edge of the crack. For samples with pre-deformation at later stage crack propagation present longer cleavage crack extension in directions along[√3,1] and[√3,-1]. And the larger the pre-deformation of sample, the quicker the expansion of cleavage crack.