An interesting GaAs based pseudomorphic high electron mobility transistor (PHEMT) with an electroless-plated (EP) surface treated gate is fabricated and studied. Based on the low-temperature and low-energy deposition conditions, the EP approach can form better metal-semiconductor (M-S) interface with the reduction in surface thermal damages and disordered-states. The material analyses of EP approach, including Auger electron spectroscopy (AES) and scanning electron microscopic (SEM), are examined. The DC performance of EP-gate device is investigated. In addition, the temperature influences of the studied devices, at the temperature region of 300 to 500K, are studied. As compared with the conventional thermal evaporation (TE) approach, the EP-based device shows significantly improved DC characteristics over a wide temperature range (300-500K). Moreover, the EP approach also has advantages of easy operation and low cost.