A sphere decoding detection method applied in a MIMO system, comprising: performing pre-processing on a received signal to obtain a signal approximate estimation value X pre of the received signal, deducing an initial square radius D 2 of sphere decoding detection according to the X pre, determining the size l of a constellation space according to a current signal to noise ratio of the received signal; searching for a search path according to the size l of the constellation space and the initial square radius D 2, wherein all nodes through which the search path passes fall within a sphere which takes the initial square radius as a radius, the searching being performed according to depth first order and sphere constraint rules, the depth-first order consisting in entering into a next layer of a tree to search rather than continuing to search for all the nodes meeting conditions in this layer after searching out one node meeting said conditions in each layer of the tree in the process of executing the tree search, the sphere constraint rules consisting in cutting off nodes of the tree that fall outside the sphere; after searching out a search path, and the sum of local Euclidean distances of the searched-out search path is less than a current square radius, updating the square radius, and within a multidimensional sphere which takes the received signal as a center of the sphere and the updated square radius as a radius, re-searching for a search path until no search path can be searched out, and determining a candidate signal point corresponding to the latest saved search path as an optimal signal estimation point; wherein the step of performing pre-processing on a received signal to obtain a signal approximate estimation value X pre of the received signal comprises: performing processing on the received signal via a semi-definite relaxation detector to obtain the approximate estimation value X pre of the received signal; wherein the step of determining the size l of a constellation space according to a current signal to noise ratio of the received signal comprises: determining that the value of the size l of the constellation space increases with the current signal to noise ratio of the received signal increasing. performing pre-processing on a received signal to obtain a signal approximate estimation value X pre of the received signal, deducing an initial square radius D 2 of sphere decoding detection according to the X pre, determining the size l of a constellation space according to a current signal to noise ratio of the received signal; searching for a search path according to the size l of the constellation space and the initial square radius D 2, wherein all nodes through which the search path passes fall within a sphere which takes the initial square radius as a radius, the searching being performed according to depth first order and sphere constraint rules, the depth-first order consisting in entering into a next layer of a tree to search rather than continuing to search for all the nodes meeting conditions in this layer after searching out one node meeting said conditions in each layer of the tree in the process of executing the tree search, the sphere constraint rules consisting in cutting off nodes of the tree that fall outside the sphere; after searching out a search path, and the sum of local Euclidean distances of the searched-out search path is less than a current square radius, updating the square radius, and within a multidimensional sphere which takes the received signal as a center of the sphere and the updated square radius as a radius, re-searching for a search path until no search path can be searched out, and determining a candidate signal point corresponding to the latest saved search path as an optimal signal estimation point; wherein the step of performing pre-processing on a received signal to obtain a signal approximate estimation value X pre of the received signal comprises: performing processing on the received signal via a semi-definite relaxation detector to obtain the approximate estimation value X pre of the received signal; wherein the step of determining the size l of a constellation space according to a current signal to noise ratio of the received signal comprises: determining that the value of the size l of the constellation space increases with the current signal to noise ratio of the received signal increasing.