Wall-mounted Flue Gas Humidity Meter HMS280 employs an anti-wear and anti-corrosion device capable of overcoming issues such as dust, high temperature, and acidic corrosion in high-temperature flue gas. It enables long-term stable online measurement of moisture in high-temperature flue gas, effectively protecting the online resistive-capacitive high-temperature flue gas moisture meter and ensuring long-term reliable operation without compromising measurement accuracy.