A triple probe array has been designed with a modified triple probe technique and utilized on the Sino-UNIted Spherical Tokamak for mode conversion research from the electron cyclotron wave to the electron Bernstein wave. The probe array is designed to measure the radial profile of the electron density in the edge region. The probe array consists of 36 single molybdenum tips, constituting 12 sets of triple probes with an interval of 6 mm in the radial direction. The three tips in each triple probe are displaced slightly in the radial direction, and thus they are not at the same magnetic surface to avoid shadow effects in the toroidal direction. A modified triple probe technique is used. The radial profile of the electron density of ohmic heated plasmas has been measured by the triple probe array. The temporal evolution of the density profile is presented, and the mode conversion processes are discussed.