Based on the cesium 6S1/2 -6P3/2 -8S1/2 ladder-type system, electromagnetically-induced transparency (EIT) is further investigated in a room-temperature vapor cell. When the probe laser is locked to one of the hyperfine transitions between the ground state 6S1/2 (F=3) and the intermediate state 6P3/2 while the coupling laser scans the transition between the intermediate state 6P3/2 and the excited state 8S1/2, the EIT spectrum has a flat background improving the spectral resolution. The theoretically calculated EIT spectral profiles from a multi-level ladder-type model are consistent well with the obtained experimental phenomena.