通过求解速率方程，从理论上详细地分析线形腔掺铒光纤激光器的输出特性。得到了稳态条件下激光器阈值泵浦功率、输出功率和斜率效率的解析表达式；给出了构造线形腔掺铒光纤激光器所需掺铒光纤最短长度和最佳长度的表达式 By solving the rate equation, the output characteristics of the erbium-doped fiber laser with linear cavity are theoretically and detailedly analyzed. The analytic expressions of laser threshold pumping power, output power and slope efficiency under steady-state conditions are obtained. The expressions of the shortest length and the optimal length of erbium-doped fiber required for constructing a linear cavity erbium-doped fiber laser are given