Long-period fiber gratings(LPFGs) are successfully inscribed in the coating-removed single mode fiber by point-by-point method.The resonant wavelength in the C band is 1 538.8 nm and its attenuation depth is above 10 dB.Further solution concentration sensing experiments of sodium chloride and sucrose show that the resonant wavelength drifts linearly to the left with the increasing of solution concentration of sodium chloride;the wavelength shift is about 0.05 nm for the salt concentration increasing by 1%,and the wavelength drifts nonlinearly to the left by about 8 nm when the sucrose concentration increases from 0% to 50%.The experimental results show that the point-by-point inscription method using femtosecond laser is simple and flexible,and it is easy to control the location of periodic refractive index perturbation in fiber core or/and cladding,so the LPFG chemical sensors which are more sensitive to low-concentration solutions can be fabricated.In addition,the LPFG written by femtosecond laser pulses has high sensitivity to the external refractive index and is expected to be used in the chemical concentration sensing.