Abstract: A nwe kind of thinned cylinder array with discrete baffle has been designed. It has adopted the discrete three-layer wideband scattering rectangular acoustical renecting baffle and the technology of array arrangement in the way that the receiving faces of array elements are arranged toward the baffle and array elements are thinly ranged. This paper shows elaborated design features of the array and calculated acoustical performances of the baffle and the array theoretically. By means of experiments made in a lake and data analysis. It has been proved that it is an advenced new cylinder array used in under-water sound measurements.