Abstract: Rapid and reliable estimation of strong ground motion (or seismic intensity) distribution based on instrumental seismic intensity can give security to earthquake emergency response soon after a destructive earthquake, especially on the situation of communication interruption. The reliabilities of eight instrumental seismic intensity algorithms are discussed using the acceleration records obtained in Wenchuan earthquake and Lushan earthquake. The results indicate that the instrumental seismic intensity evaluated by peak parameters of ground motion, such as PGA or PGV, are of lower reliabilities than the instrumental seismic intensity derived from response spectra. We suggest that the instrumental seismic intensity evaluated by Professor Yuan's algorithm, by Housner's spectrum intensity, or by response spectra, could be accepted in China until more data are available to propose a more reliable algorithm.