Current Sheets (CSs) are the main region where magnetic reconnections can convert magnetic energy into plasma thermal and kinetic energies. We have studied a CS in the streamer observed on 3 January 2003 by combining the White-Light (WL) images observed by the Large Angle and Spectrometric Coronagraph (LASCO) and the UV spectra detected by the Ultraviolet Coronagraph Spectrometer (UVCS). LASCO C2 WL data showed that the velocity of a blob in the CS increased from 60km$\cdot $s^-1 to 340km·s^-1 with an acceleration of 60m·s^-2 in its field of view. Assuming the light-of-sight (LOS) depth of 0.3--1.5R _{⊙<.sub>, the average electron number density of the CS was (1.52--7.60)× 10⁷cm^-3 at the height of the UVCS slit. We investigated the intensity distributions of the [Fe xviii ] 974 ? A and Lyα lines along the UVCS slit. It is shown that the intensity of [Fe xviii ] line in the CS was significantly higher than those of the surroundings, and the deduced electron temperature range of the CS was (2.94–4.04)×10 6 K during the studied period. However, the intensity of the Lyα line in the CS did not change much when compared with those of the surroundings, and within the CS the intensity on both sides were slightly higher than that in the center. It is possible that the plasma moved faster in the center, and resulted in stronger Doppler dimming effect. Using the observed intensity ratio of Lyα and [Fe xviii ] lines observed by UVCS and the calculated electron temperature as constraints, we found that the theoretically calculated emissivity ratio of Lyα and [Fe xviii ] lines was close to their observed intensity ratio when the plasma velocity range was 237–254 km·s ^?1 at the position of the CS. The collisional component of the Lyα line was about 42%–57% of the radiative component in the CS within the speed range above. The streamer CS we studied had a higher plasma temperature and a faster blob speed than the typical values in normal situations. The possible reason is that the two CMEs at the southern side enhanced the magnetic reconnection process in the CS, and more magnetic energy was released to heat and accelerate plasma. Our results on the CS can be regarded as pre-studies of the data analyses for the future mission of the Advanced Space-based Solar Observatory (ASO-S).}