An　improved　non-iterative　multiple　signal　classification　(INI-MUSIC)　algorithm　was　proposed　to　solve　the　problem　of　low　estimation　accuracy　of　rotation　iterative　algorithm　under　the　condition　of　mixed　mutual　coupling　error　and　amplitude　gain　error.　The　improved　algorithm　used　the　special　properties　of　the　error　coefficients　under　a　uniform　circular　array　and　the　matrix-vector　conversion　theorem　to　separate　the　amplitude-phase　error　and　the　mutual　coupling　error　from　the　DOA　estimation,　so　as　to　realize　the　dimension　reduction　operation　under　the　mixed　error.　Then　the　cost　spectrum　peak　function　was　reconstructed　to　compensate　the　loss　of　rank　and　to　obtain　the　estimation　of　the　DOA　angle　and　the　joint　estimation　of　the　error　coefficient.　The　probability　of　error　spectrum　peaks　was　reduced　by　the　proposed　algorithm,　which　has　better　two-dimensional　DOA　estimation　accuracy,　and　has　higher　engineering　application　value.　©　2022,　Editorial　Department　of　Journal　of　Beijing　University　of　Technology.　All　right　reserved.