In this paper, we present a theoretical model to describe the passively-Q output characteristics of quasi-three level Ho<sup>3+</sup>-doped Fluorotellurite fiber lasers. According to the model, we have studied the factors impacting on the output characteristics of the laser through numerical simulation method. The calculating program of the theoretical model is written using the Matlab language. We obtain the passively-Q output laser with the pulse repetition rate of 13.1 kHz, pulse width of 28.63ns, peak power of 25W, and pulse energy of 0.34 μJ at the pump power of 0.1W. When the pump power increases, the pulse width of the laser decreases, the pulse repetition rate linearly increases, both the pulse energy and the peak power also increases. The pulse width of the laser linearly increases and the pulse energy increases when the length <i>L</i> does. When the output coupler transmission T increases, both the pulse width and the peak power of the laser decrease. The pulse energy of the laser firstly increases and then decreases when the output coupler transmission <i>T </i>does. We qualitatively analyze what causes the change laws of the outputlaser characteristics, such as the pulse width and the pulse energy.