Abstract: A LD pumped passively Q-switched and Q-switched mode-locked Tm, Ho: LLF laser using graphene oxide as saturable absorber was reported. Using output mirrors with transmittance of 3%, 5% and 9%, the continuous operation characteristics of Tm, Ho: LLF laser were studied. The experimental and simulation results show that the output mirror with 9% transmittance has the best output characteristics. When the maximum pump power is 20 W, the CW output power is as high as 1793 mW. Then, the Q-switched and Q-switched mode-locked characteristics of Tm, Ho: LLF laser were studied by using graphene oxide as saturable absorber under OC with 9%. The experimental results show that when the pump power of 790 nm LD is less than 7.26 W, the laser is in a simple Q-switched state. When the power is greater than 7.26 W, the laser operation enters into a stable Q-switched mode-locked state. When the maximum pump power is 20 W, the maximum output power is 1052 mW, the repetition rate of mode-locked is 53.19 MHz, and the corresponding average single pulse energy is 19.77 nJ. This average single pulse energy is currently the highest level of a 2 μm mode-locked laser. At the same time, it is confirmed that graphene oxide is a promising two-dimensional mode-locked material in high-energy mode-locked lasers.