Abstract: When high power laser transmits in the atmosphere,thermal blooming will be generated.In order to study the phenomenon,the effect parameters to steady-state thermal blooming without wind are solved in detail by numerical simulation.It is studied that both epaxial light intensity and energy distribution at far field are affected by steady-state thermal blooming without wind.The study results indicate that as emission power increases,the peak power density on the section of a certain distance will increase firstly,then it will descend and that the peak light intensity on the section will increase with the increasing of spot radius of basic mode Gaussian beam.As the propagation distance increases,the peak light intensity on the section will descend gradually,and the laser energy will spread.The light intensity distribution exhibits straw hat shape on a certain conditions,in other word to say,the central light intensity is less than acroteric light intensity.The results is helpful to the research of high power laser's irradiation effect at far field.