KTiOPO4 samples were implanted by Bi+ ions with energies from 100 to 350 keV in increments of 50 keV. The depth distribution and diffusion behavior of implanted Bi+ into KTiOPO4 were investigated by normal and oblique incidence Rutherford backscattering. The results show that the maximum difference between experimental and calculated values of the mean projected range is less than 22%; the experimental range straggling somewhat deviates from the prediction by TRIM'98. After annealing, the redistributions of implanted Bi+ ions in KTiOPO4 do not obey Fick's law, and there is a segregation process to the surface for 700 degreesC annealing. After 800 degreesC annealing for 30 min, most of the segregated Bi+ ions had evaporated, and the distribution of the remaining Bi+ ions became flat.