This paper presents a study on `hard' and `soft' interactions in p (pp) collisions using a phenomenological model of HIJING, the jet-cone reconstruction method is employed to select the `hard' and `soft' event sub-samples from minimum bias events. It is found that the HIJING model can reproduce the energy scaling behaviour of mean transverse momentum ( ) distributions of charged hadrons versus multiplicity (Nch) in `soft' events. From the PYTHIA simulation comparing with the HIJING model, the enhancement of the kaon and proton yields from `hard' interactions comparing with `soft' interactions is observed to be due to the mini-jets effect. These mechanisms responsible for the increase of charged hadron's are different in `soft' and `hard' interactions.