To improve the practicability of the Er∶Yb co-doped fiber laser,the self-pulse phenomena is discussed theoretically. Based on two theories a system model is setup. One is the saturable absorption of the Er ion-pair in the co-doped fiber will lead to self-pulsing;the other is the interplay between the ion-pairs. The effective pump rate for Er-doped fibers by Yb codoping is analyzed. It is shown that the level of the pump power required to suppress the ion pair induced self-pulsing in Er-doped fiber lasers can be significantly decreased by using Yb:Er codoped fiber due to the increased effective pump rate. The output pump power of the laser diode is high enough to restrain this kind of self-pulse, which support stable laser operation. The result shows that the potential of developing stable single-frequency or high-repetition-rate mode-locked fiber lasers by using high gain Yb:Er codoped fibers with laser diodes as pump sources.