411201，Hunan，China;

2. School of Ｒesource Environment and Safety Engineering，Hunan University of Science and Technology，Xiangtan 411201，

Hunan，China;

3. School of Geosciences and Info-physics，Central South University，Changsha 410083，China;

4. School of Ｒesource Environment and Tourism，Hunan University of Arts and Science，Changde 415000，Hunan，China

the authors use clustering method to analyze the Euler solution set，which is obtained by solving the Euler homogeneous equations with truncated singular value decomposition． Each large linear equations formed by Euler deconvolution on a square moving window have the excessive conditions number． This phenomenon easily leads to the non-uniqueness and instability of Euler solutions and is estimated by truncated singular value decomposition． Furthermore，the proportion of the optimal solution in Euler solution set with different sized moving windows for

same sized anomalous sources is compared and analyzed，so as to analyze the proportional relationship between the size of moving window and the size of anomalous source，and the size of optimal moving window was determined．

The model experiment results show that when the distance between the survey grids is one tenth of the size of the abnormal source，the size of optimal moving window should be 3 times the size of the anomalous source and less

than 0. 5 times the size of the exploration area．