Lateral constrain in the presence of melting has a significant effect on microstructure evolution of crystal growth, and this effect is related to the size and property of lateral constrain, thus determining microstructure formation during solidification. In the paper, microstructure evolution in the presence of lateral constrain during the solidification of pure Ni metal is simulated using a non-isothermal phase-field model. Effects of size and properties of lateral constrain are simulated and studied, also microstructures formed at different initial dendritic arm distances are discussed. Results indicate that the presence of lateral constrain has a direct influence on pattern evolution which determines the microstructure formation. Microstructure changes significantly with lateral constrain distance turning small, initial constrain temperature low becoming low and initial dendrite arm distance growing. Different heights of lateral constrains have almost the same effects on microstructure change during solidification.