Based on Maxwell's stress tensor theory， the photodynamic properties of polygonal gold nanoparticles in a focused field were studied. Taking triangular gold nanoparticles as an example， the trapping characteristics of triangular gold nanoparticles in focusing field with circular symmetric energy distribution and with triangular energy distribution were studied respectively from the stress conditions of the particles in the focusing field. The results show that the triangular gold nanoparticles with side length of 50~350 nm can be stably captured by using the circular symmetric focusing field. When the triangular focusing field is used， the triangular gold nanoparticles with side length of 100~350 nm can be stably captured under the condition that the particles enter the focusing field at an angle matching the shape of the focusing field. The trapping properties of triangular gold nanoparticles were compared between the circular symmetric focusing field and the triangular focusing field， and we found that the trapping force of the triangular focusing field in the x direction was stronger than that of the circular symmetric focusing field. In the y direction， the capturing range of the triangular focusing field is larger than that of the circular symmetric focusing field. In this work， we studied the optical trapping properties of triangular metal nanoparticles in different focused fields， and laid a theoretical foundation for the application of optical manipulation based on non-spherical metal particles in Raman super-resolution imaging， particle micro-processing and other fields.