A method for measuring wet gas flow, the method comprises the steps of: (a) measuring the total flow differential pressure value ΔP of wet gas in a pipeline (601,801,901) via a differential pressure type flow measuring device (602,802,902); (b) measuring gas void fraction of the wet gas in the pipeline (601,801,901) via at least two phase fraction meters (603,803,903), respectively; (c) obtaining optimized gas void fraction GVF opt by a flow calculating module based on the gas void fractions respectively measured by the at least two phase fraction meters (603,803,903); and (d) calculating the gas volume flow rate Q g and the liquid volume flow rate Q l by the flow calculating module, based on the total flow differential pressure value ΔP and the optimized gas void fraction GVF opt of the wet gas; characterized in that the step (c) comprises the following steps: calculating the short-term local reliability function F () of the gas void fraction Xi measured by each phase fraction meter: F ( X i) = D ( X i) = E ([ X i - E ( X i)] 2), wherein Xi denotes the time sequence of the gas void fraction measured by the phase fraction meter i, 1≤ i ≤N; N denotes the number of phase fraction meters; D () denotes a variance function; and E () denotes an expectation function; constructing a long-term whole reliability function LF () for the gas void fraction Xi measured by each phase fraction meter: S i 0 = X i 0, S i m = αS i m − 1 + 1 − α X i m, LF S i = D S i, wherein 0≤α≤ 1, and 0≤m≤M-1, where M denotes the number of the gas void fractions included in the time sequence, and X i [ m] denotes the m th gas void fraction in the time sequence of the gas void fraction measured by the phase fraction meter i; constructing a comprehensive reliability function NICE () for the gas void fraction Xi measured by each phase fraction meter by utilizing the short-term local reliability function F () and the long-term whole reliability function LF(): NICE X i = 1 F X i + LF S i; and obtaining the optimized gas void fraction GVF opt by utilizing the comprehensive reliability function NICE (): GVF opt m = ∑ i = 1 N X i m NICE X i ∑ i = 1 N NICE X i, wherein GVF opt [ m] denotes the m th optimized value in the time sequence of the optimized gas void fraction GVF opt. (a) measuring the total flow differential pressure value ΔP of wet gas in a pipeline (601,801,901) via a differential pressure type flow measuring device (602,802,902); (b) measuring gas void fraction of the wet gas in the pipeline (601,801,901) via at least two phase fraction meters (603,803,903), respectively; (c) obtaining optimized gas void fraction GVF opt by a flow calculating module based on the gas void fractions respectively measured by the at least two phase fraction meters (603,803,903); and (d) calculating the gas volume flow rate Q g and the liquid volume flow rate Q l by the flow calculating module, based on the total flow differential pressure value ΔP and the optimized gas void fraction GVF opt of the wet gas; calculating the short-term local reliability function F () of the gas void fraction Xi measured by each phase fraction meter: F ( X i) = D ( X i) = E ([ X i - E ( X i)] 2), wherein Xi denotes the time sequence of the gas void fraction measured by the phase fraction meter i, 1≤ i ≤N; N denotes the number of phase fraction meters; D () denotes a variance function; and E () denotes an expectation function; constructing a long-term whole reliability function LF () for the gas void fraction Xi measured by each phase fraction meter: S i 0 = X i 0, S i m = αS i m − 1 + 1 − α X i m, LF S i = D S i, wherein 0≤α≤ 1, and 0≤m≤M-1, where M denotes the number of the gas void fractions included in the time sequence, and X i [ m] denotes the m th gas void fraction in the time sequence of the gas void fraction measured by the phase fraction meter i; constructing a comprehensive reliability function NICE () for the gas void fraction Xi measured by each phase fraction meter by utilizing the short-term local reliability function F () and the long-term whole reliability function LF(): NICE X i = 1 F X i + LF S i; and obtaining the optimized gas void fraction GVF opt by utilizing the comprehensive reliability function NICE (): GVF opt m = ∑ i = 1 N X i m NICE X i ∑ i = 1 N NICE X i, wherein GVF opt [ m] denotes the m th optimized value in the time sequence of the optimized gas void fraction GVF opt.