The correlations between the shape of rapidity distribution of the yield of light charged particles and the fragmentation modes in semi-peripheral collisions for 70 Zn+ 70 Zn, 64 Zn+ 64 Zn and 64 Ni+ 64 Ni at the beam energy of 35MeV/nucleon are investigated based on ImQMD05 code. Our studies show there is interplay between the binary, ternary and multi-fragmentation breakup modes. The binary and ternary break-up modes more prefer to emit light charged particles at middle rapidity and give larger values of R mid yield compared with the multi-fragmentation break-up mode does. The reduced rapidity distribution for the normalized yields of p, d, t, 3 He, 4 He and 6 He and the corresponding values of R mid yield can be used to estimate the probability of multi-fragmentation break-up modes. By comparing to experimental data, our results illustrate that ≥40% of the collisions events belong to the multi-fragmentation break-up mode for the reaction we studied.Fragmentation mechanism, i.e. does a nucleus break up into several intermediate mass fragments (IMFs) in intermediate energy heavy ion collisions (HICs) in a statistical (thermal) way or dynamical way, has been a longstanding problem in nuclear physics, and it has attracted a lot of theoretical