By using bi-direction of the fiber cross-section asymmetric CO2 laser pulses exposure approach, the long period fiber grating (LPFG) sensing characteristics can be controlled and improved. This fabrication method is to write the LPFG on one side by CO2 laser, and then write the LPFG again on the other side with the same grating pitch and exposure energy. Under the action of the two exposure directions, the fiber refractive index was periodically modulated twice. Asymmetric thermal stress analysis results shown that the resonant peak of LPFG can shift in direction of either shorter or longer wavelengths, depending on the angle difference Δθ between two exposure directions changes in the second writing process. It is confirmed by the experimental results. We found this technique could be used in wavelength tunable LPFG fabrication or fiber optic sensors design to control and improve the characteristics of the components.