In this paper, we propose a new scheme front-end of the 2 μm OPCPA system. The visible and near-IR supercontinuum spectra are realized through dual laser filamentation processes based on different YAG crystals. The 2 μm laser seed pulse is produced by the DFG process between the two supercontinuum spectra’s difference and amplified by two optical parametric amplification stages. The amplified spectrum of seed laser ranges from 1830 to 2320 nm with a bandwidth of 243 nm. The amplified pulse laser has average power, single pulse energy, pulse duration, and pulse repetition rate of 167 mW, 16.7 μJ, 29 fs, and 10 kHz, respectively. The beam quality M² factor is less than 1.3. It is expected that the pulse energy of 2 μm laser seed pulse can be further amplified to the mJ-level and peak power to GW-level for further driving the noble gas to generate water-window X-ray.