This paper reports the experimental observation of the excitation energy transfer to higher states by collisions between two rubidium atoms excited to a specific state by a CW single mode laser. An obvious competition has been observed between the channel of transition to the ground state by spontaneous emission, and that to higher excited states by collisions of two excited atoms. Formation rates of the high excited states with different laser power, atomic vapor temperature and laser detuning have been measured. A proposed mechanism well explained the experimental result.