Abstract: Fiber lasers, with their advantages of high efficiency, strong stability, and miniaturization, have been widely used in modern fiber optic wavelength division multiplexing communication systems, driving their development towards multi-channel direction. In this paper, a multi-wavelength Erbium-doped fiber laser (MWEDFL) based on coreless and seven-core fiber structure filter is proposed, and its spectral performance is tested. Additionally, to verify the tunability of the fiber filter structure, temperature and strain tunability experiments are conducted. The research results indicate that by adjusting the polarization controller (PC), the developed MWEDFL can achieve switchable fiber laser output of multi-wavelength and precise adjustment of wavelength position. The optical signal-to-noise ratio of lasers of various wavelengths excited by the MWEDFL is higher than 28 dB, with a maximum of 47.88 dB, while the wavelength shift and peak power fluctuations are less than 0.34 nm and 6 dB, respectively. Furthermore, the tunability experiments demonstrate that within the temperature range of 26~50 °C, the wavelength shift of the fiber laser is less than 0.92 nm, and the power fluctuation is less than 4.18 dB. In the strain range of 0~2 mm, the wavelength displacement is less than 0.11 nm and the power fluctuation is less than 3.20 dB.