A new perovskite-like inorganic -organic hybrid compound [Et-3(n-Pr)P][Cd(dca)(3)] (1) (where [Et-3(n-Pr)P](+) is the propyltriethylphosphonium cation and dca is a dicyanamide ligand) was discovered to undergo three reversible phase transitions at 270 K (T-1), 386 K (T-2), and 415 K (T-3), respectively. The variable -temperature single -crystal X-ray structural analyses reveal that these sequential phase transitions originate from the deformations of the [Cd(dca)(3)](-) frameworks and the concomitant reorientations of the [Et3(n-Pr)P] guest cations. It is found that 1 possesses a sensitive nonlinear optical (NLO) switching at T-2 with a large contrast of,similar to 40 within a narrow temperature range of K. Furthermore, 1 shows intriguing photoluminescence (PL) property, and the PL intensity suffers a plunge near T-3. The multiple phase transitions, switchable NLO and tunable luminescent properties simultaneously exist in this inorganic -organic perovskite-like hybrid compound, suggesting its great potential application in molecular switches and photoelectric field.