This paper presents the measurement results of absolute cross-sections of ion-atom collision in detail. The pure cross-sections of Nei+(i=1—4) induced by C3+ were investigated using coincidence technique. Comparing our experimental results with those of n-body classical trajectory Monte Carlo method, it is found that the changes of pure cross sections with increasing energy have the same trend in the two cases. The causes of discrepancies between them are discussed. The mechanism of multiple-ionization is analyzed. The highly charged recoil ions come mainly from the Auger effect. The electron-electron interaction comes in to effect as the incident energy increases. The cross-sections of all kinds of reactions can be measured in this way using the same equipment and projectile ions can be various within a wide range of energy.