A rapid micellar extraction and pre-concentration method by ultrahigh pressure-assisted was developed for four alkaloids in Nelumbo nucifera leaves. Nonionic surfactant polyoxyethylene octylphenol ether (OP-10) solution was selected as solvent. Various experimental conditions were investigated to optimize the extraction and pre-concentration process. The optimal UPE condition was 5% OP-10 (w/w) solution, 400 MPa of pressure, 1 min of extraction time, and 1:20 (g/mL) of solid/liquid ratio. The pre-concentration of alkaloids was achieved by cloud-point extraction (CPE) and the optimum CPE condition was incubated in a thermostatic water bath at 55 degrees C for 10 min, with 10% OP-10 and 15% sodium chloride added into the solution. The pre-concentration factor (CF) value was 11.6 +/- 0.127, and the CPE recoveries for O-nornuciferine, N-nornuciferine, nuciferine, and roemerine were 91.0%, 92.3%, 92.7%, and 94.5%, respectively.