A pressure sensing method and a system thereof are disclosed. The pressure sensing method includes following steps. Stored resistance values Rn are read and a differential resistance value ΔRn between resistance valises at adjacent moments are calculated. At least one ΔRn/Rn−1 is obtained. The at least one ΔRn/Rn−1 or a sum of plural ΔRn/Rn−1 is compared to at least one predefined database. A pressing force value Fn corresponding to the at least one ΔRn/Rn−1 or the sum of the plural ΔRn/Rn−1 is obtained, so as to detect and process a pressure sensing signal precisely.