The long period fiber grating must be written and used under stress. In this paper, the effects of stress on the central wavelength and attenuation depth of resonance wave during and after writing of the long period fiber grating are analyzed in detail by experimental method. It is found in the experiment that the stress has no influence on the central wavelength of the resonant wave, but has a greater influence on the attenuation depth of the resonant wave, and the influence of the stress on the performance of the long period fiber grating at different stages is different. When writing, the stress provided by 40 g weights can be used to write long period fiber grating with good characteristics and the performance of the long period fiber grating can be further improved by increasing the stress after writing.