The tunability and high gain amplification of (Tm,Ho)∶YLF crystal with wide spectral band in the range from 2047～2070 nm are studied in theory and experiment. The crystal length and (Tm,Ho) doped concentration are optimized for room operation and high gain amplification. The microchip Tm(fraction of number of atoms 0.06),Ho(fraction of number of atoms 0.004)∶YLF laser is tunable from 2.0656～2.0671 μm under pumping power of 1.88 W at 792 nm. The 2.048 μm radiation from (Tm,Ho)∶GdVO4 laser is amplified by cryogenic Tm(8%), Ho(1.4%)∶YLF amplifier dual-end pumped by two 15 W fiber-coupled laser diodes, an amplification factor of 2.5 is achieved. The blue-green upconversion fluorescence spectral from (Tm,Ho)∶YLF laser under strong pumping condition are measured within the radiation range of 480～492 nm and 530～550 nm.