Fragment yields of projectile fragmentation reactions using primary beams of $^{ 36,40 } Ar$ at 50 MeV/nucleon on $^ {64}$Ni target have been measured, fragment separator RIBLL and particle identification were discussed in detail.Fragment yields of different isotopes were obtained for Z >=5 in RIBLL fragment separator.We compare the extracted yields to the predictions of the empirical parameterization of fragmentation cross-sections(EPAX) and Statistical Abration-Ablation model(SAA).Considering the RIBLL transmission rate, EPAX and SAA simulation can fit the experimental cross section well.Isotope yield ratios were calculated from 2 measured reactions and isoscaling effect of the produced isotopes was also observed, lsoscaling was also calculated from the EPAX and SAA calculation result.Isospin effect and symmetry energy were discussed from isoscaling.