High pulse-energy semiconductor saturable absorber mirror passively mode-locked thulium-doped femtosecond fiber laser is reported. Based on a linear Fabry-Perot cavity by the combination of semiconductor saturable absorber mirror and broadband reflective mirror, the thulium-doped fiber is pumped by a home-made Er-doped fiber laser at 1550 nm. Stable mode-locked laser pulse train occurs at 312 mW incident pump power and the pulse repetition rate is 53 MHz in such a linear cavity configuration. When the incident pump power is 472 mW, the maximum output power is 50 mW, corresponding to the maximum single pulse energy of 0.94 nJ. The pulse width is measured to be 907 fs; the laser center wavelength and the 3 dB spectral bandwidth are 1939.5 nm and 4.6 nm, respectively.