We report on stable passively harmonic mode-locking dissipative pulses with high repetition rate and narrow bandwidth in 2µm Tm: CaYAlO4 laser. At the large intracavity intensity, the laser generated 1st-order to 5th-order passively harmonic solitons with fundamental repetition rate of ~198 MHz and 5th-order repetition rate up to 0.98 GHz, which was mainly caused by the peak power clamp effect. The solitons yielded a tunable central wavelength from 1940nm to 1950 nm, and a narrow optical spectrum bandwidth of 60 pm without any active optical filter. At low intracavity intensity, the laser operated on the typical SESAM-guided mode-locking mode, with the scaled output average power up to 1.15 W. To our knowledge, this is the first observation of passively harmonic mode locking in 2µm solid laser system, and the first Watt-level output average power in Tm: CYA mode locking laser.