A special uniform circular array (SUCA) was fixed on the underwater monitoring system’s floater system; SUCA’s model was created based on SUCA’s particularity. Then half-power beamwidth and unambiguous condition of SUCA were reseabased by theory of mode-space. Results show that half-power beamwidth and unambiguous condition’s scope of SUCA is wider than UCA, and SUCA is practicable in engineering application.