In this paper, high-resolution vib-rotational spectrum of ultracold cesium molecule in its first excited state of 6S1/2+6P3/2 with dissociation limit 0g- long range state is obtained by cold atom fluorescence frequency modulation method. The rotation constants of different vibration energy levels of cesium molecule for vibrational quantum number from 0 to 51 are achieved. The results are in good agreement with the theoretical results given by Daniel.