To ensure the long-term fire-retardant (FR) and anti-mildew (AM) of bamboo materials when employed in outdoor settings susceptible to rainfall exposure, high durability is essential. In this study, we achieved water-leaching resistance of FR and AM bamboo through the in situ synthesis of phosphotungstic acid (PW) and silver nitrate (AG) via vacuum-pressure impregnation. The successful synthesis of the nanospheres within the bamboo (referred to as PWAG-B) was confirmed by TEM, FTIR, and XPS. These nanospheres remained intact within the bamboo cell wall after being subjected to a leaching test, ...