A method for detecting blade imbalance of a doubly-fed wind power generator system based on stator current data, comprising steps of: 1) collecting, on a condition of blade balance, a plurality sets of data during a time period where the doubly-fed wind power generator system operates at a constant rotational speed, each of the plurality sets of data comprising a stator phase current i A and a rotational speed r, and performing a Hilbert transform on the stator phase current i A, to obtain an amplitude envelope signal, wherein no pitch operation is performed in collecting the data; 2) performing a FFT transform on the amplitude envelope signal obtained in step 1, and calculating a base rotational frequency f of an impeller based on the rotational speed r of the doubly-fed wind power generator system; 3) determining an amplitude at the base rotational frequency of the impeller based on results obtained in steps 1) and 2), and performing a fitting operation with a least square method to obtain a curve for showing a relationship between the amplitude at the base rotational frequency and the stator phase current in the case of blade balance; 4) collecting the stator phase current i A and the rotational speed r during the time period where the doubly-fed wind power generator system operates at the constant rotational speed, and calculating an amplitude Q at the base rotational frequency according to steps 1) and 2); 5) calculating Q_base based on the stator phase current collected in step 4) in conjunction with the curve obtained in step 3), wherein Q_base indicates a reference amplitude at the base rotational frequency; and 6) comparing Q with Q_base + offset, and determining that there is the blade imbalance in a case that Q > Q base + offset, wherein an imbalance degree is calculated based on a difference between Q and Q_base + offset, and wherein the offset indicates a residual compensation and is determined based on theoretical analysis and the collected plurality sets of data in combination with an influence of residual in the least square method. 1) collecting, on a condition of blade balance, a plurality sets of data during a time period where the doubly-fed wind power generator system operates at a constant rotational speed, each of the plurality sets of data comprising a stator phase current i A and a rotational speed r, and performing a Hilbert transform on the stator phase current i A, to obtain an amplitude envelope signal, wherein no pitch operation is performed in collecting the data; 2) performing a FFT transform on the amplitude envelope signal obtained in step 1, and calculating a base rotational frequency f of an impeller based on the rotational speed r of the doubly-fed wind power generator system; 3) determining an amplitude at the base rotational frequency of the impeller based on results obtained in steps 1) and 2), and performing a fitting operation with a least square method to obtain a curve for showing a relationship between the amplitude at the base rotational frequency and the stator phase current in the case of blade balance; 4) collecting the stator phase current i A and the rotational speed r during the time period where the doubly-fed wind power generator system operates at the constant rotational speed, and calculating an amplitude Q at the base rotational frequency according to steps 1) and 2); 5) calculating Q_base based on the stator phase current collected in step 4) in conjunction with the curve obtained in step 3), wherein Q_base indicates a reference amplitude at the base rotational frequency; and 6) comparing Q with Q_base + offset, and determining that there is the blade imbalance in a case that Q > Q base + offset, wherein an imbalance degree is calculated based on a difference between Q and Q_base + offset, and wherein the offset indicates a residual compensation and is determined based on theoretical analysis and the collected plurality sets of data in combination with an influence of residual in the least square method.