A method for realizing a stable multiwavelength erbium-doped fiber laser at room temperature is analyzed theoretically and obtained experimentally. A sinusoidal phase modulation is inserted in the linear cavity, which suppresses the mode competition owing to the homogeneous broaden line in eribum-doped fiber and eliminates the unstable single-wavelength lasing at room temperature. What′s more, the spatial hole burning in linear cavity is propitious to suppress the homogeneous broaden line. Simultaneous five-wavelength lasing is obtained with 0.8 nm intervals defined by the sampled fiber Bragg grating, which is anchored on the ITU frequency grid.