To meet the demand for the precise measurement of ammonia (NH?), this paper proposes an ammonia concentration measurement technology using femtosecond laser filament-triggered discharge. Through long filament-triggered discharge formed in air by femtosecond laser pulses, the plasma emission spectra of NH? under different conditions were obtained by using a spectral acquisition system. The calibration curve for NH? concentration was obtained by utilizing the ratio of peak areas of characteristic spectral lines in the emission spectra. The one-dimensional spatial distribution of the spectral line intensity was analyzed. The research results demonstrate that the ratio of characteristic spectral line peak areas exhibits excellent linear response to NH? concentration, and the one-dimensional spatial distribution of characteristic spectral line intensities exhibits good stability. The NH? concentration measurement technology based on femtosecond laser filament-triggered discharge enables real-time quantitative ammonia measurement, providing a new method for real-time in-situ detection of NH?.