The finite difference time domain (FDTD) method was used to calculate the output optical fields of parabolic and large angle single-fiber optical tweezers. The transverse and axial trapping forces were then obtained by integrating the Maxwell stress tensor in stable state. Compared with the parabolic fiber optical probe, the optical force of the large angle fiber probe is lager. Meanwhile, the influences of sizes and diffractive indexes of microscopic particles and profile of fiber probe on the optical force were considered. In experiment, these two fiber probes both successfully trap yeast cells in water and the two types of force are calibrated by hydromechanics. The results indicate that the optical force obtained by numerical simulation based on FDTD is in good agreement with that from experiments. This method is simple and suitable for the optical force calculation of fiber optical tweezers, and the parabolic and large angle optical fiber tips meet the demand of forming single-fiber optical tweezers.