Rb atoms were excited to the 5P3/2 level using a single-mode laser diode. The 5P3/2 state atom density was measured bv the absorption of line from a Rb hollow-cathode lamp. The excited atom density is combined with measured fluorescence ratio to determine collisional cross section for the energy pooling process [i.e. Rb（5P3/2）＋Rb（5P3/2）→Rb（5D）＋Rb（5S）]. The cross section is （5.0＋1.9）×10^-14cm^2. Cross section for 5P3/2 →5P1/2 transfer in Rb, induced in collision with ground-state Rb atoms, has been determined using methods of atomic fluorescence. The resulting fluorescence included a direct component arising from the optically excited state and a sensitized component due to the collisionally populated fine-structure state and the energy-pooling collisions. Measurement of relative intensities of the two components yielded the following cross section： σ （5P3/2 →5P1/2）=（3.0＋0.9） ×10^-15cm^2. it is found that the rate for the energy pooling is an order of magnitude more efficient than 5P3/2→5P1/2 mixture. Comparisons of our result with other experiments have been made.