Abstract: In this paper, the spontaneous emission of Langmuir waves is discuss due to energetic electrons produced by solar flares in the solar wind. It is found that the electric field of the spontaneously emitted Langmuir waves can be as large as 10^-3-10^-2mV/m(depending upon the distribution of the electrons),if considering a characteristic time of γ_km^-1, where γ_km is the peak growth rate. This results is a great deal lower than the electric field associated with Langmuir waves observed with spacecraft in the solar wind. Thus, compared with induced processes,the spontaneous emission of Langmuir waves in general is negligible.