The generation and evolution of soliton molecules are investigated theoretically with the coupled nonlinear Schrodinger equations based on a vector field. The formation of second-and third-order soliton molecules is investigated. Besides this, various-order soliton molecules from the 6th order to the 13th order have been observed by adjusting small-signal gain and phase delay. Finally, we analyze the reason for the soliton molecule generation. Exploring soliton molecules is helpful for optical communication as well as for fiber laser design.