An improved complex vector radius virtual source method based on sound pressure measurement is adopted to research radiation sound field of typical underwater structures and noise reduction character of its viscoelastic material.The boundary element method（BEM） software SYSNOISE is applied to obtain sound pressure on measurement surface

pulsating sphere sound radiation model is used to verify the correctness of software computation

is verified and effectiveness of complex vector radius method by sphere shell sound radiation under single point excitation.Research results show that combining acoustic impedance transferring and interface coupling theory

precision of sound field computation can be improved by optimizing complex vector radius ratio and positions of double spherical virtual source in cylindrical shell under single point excitation

the complex vector radius method is more operational and practical than traditional virtual source superposition method in engineering.