The effective pump rate for Er doped fibers by Yb codoping was analyzed theoretically.We show 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.Our result show that the Er:Yb codoped fiber laser not only increases the lasers efficiency but also stabilizes the laser output.