In order to obtain electromagnetically-induced transparency (EIT) spectra with high signal-to-noise ratio (SNR), EIT has been investigated based on the cesium (Cs) 6S1/2-6P1/2-8S1/2 ladder-type atomic system. When the probe laser which couples the Cs 6S1/2-6P1/2 transition is frequency locked to hyperfine transition and the controlling laser scans over the Cs 6P1/2-8S1/2 hyperfine transition, the narrow EIT spectra with a flat background is observed, and the spectral SNR is improved. The signal intensity of EIT hyperfine structures depends on not only the alignment of controlling and probe beam, but also the intensity of the controlling laser in ladder-type system. Finally, the EIT spectra with high SNR is obtained.