Improving the energy concentration of the main lobe and suppressing the grating lobe are the key to the application of optical fiber laser phased array technology. In this paper, the cutting point was the reason why laser phased array was difficult to satisfy the element spacing of λ/2 and then many grating lobes were produced. Considering the problem that the aperture of the phased array was enlarged by the method of suppressing the unequal-spacing grating lobe, a new idea of introducing genetic algorithm into the optimization of element distribution of optical fiber laser phased array was proposed. The main method was to propose a fitness function related to the main lobe energy concentration and the main lobe/side lobe contrast from the perspective of the maximum suppression of the lobe. The characteristic parameters of genetic algorithm were corresponded to the main parameters of fiber laser phased array. Then, taking two kinds of linear arrays as an example 20 line array element/array element interval as 3 times wavelength and 50 line array element/array element interval as 20 times wavelength, the traditional equally spaced array elements and unequal spacing, the array element distribution and the genetic algorithm optimized the array element distribution were simulated respectively. The distribution of the far-field energy, the main lobe energy concentration and the contrast between the main lobe and the maximum lobe of the fiber laser phased array were calculated and compared. The results show that the energy concentration of the main lobe is increased by 9.69% and 3.33% respectively, and the energy contrast between the main lobe and the first grating lobe is increased by 13.12% and 9% respectively. It can be seen that the phased array optimized based on genetic algorithm is expected to obtain a longer working distance under the same total power of laser emission.