Abstract: Fiber loading technology can be used to improve both fiber bond and paper ash content. The effects of pulp concentration, rotating speed, CO2 pressure and reaction time on the fiber loading mechanical pulp were studied in this paper. The L4 experiment was designed to test effect. The results showed that the rotating speed was the key factor; and fiber loading method was feasible for mechanical pulp. The Scott, breaking length and bursting strength of fiber loaded handsheet using BCTMP were improved by 17.86%, 42.86% and 42% respectively of it was compared with direct loading. The ash content of that handsheet was improved by 2.05%. On the other hand, the Scott of fiber loaded handsheet using APMP were improved by 21.31%, 6.56% and 1.64% respectively, the breaking length of that handsheet were improved by 69.18%,77.40% and 75.34% respectively. The bursting strength of that handsheet were improved by 18.18%, 22.73% and 25% respectively, while the ash content of that handsheet were improved by 9.62%, 1058% and 1.68% respectively. The effect of fiber loaded APMP was better than that of BCTMP.