The present invention disclosed a method to produce a slow release lipid nanoparticles comprising steps of determining a log P value of an active ingredient; mixing fatty acid, non-ionic surfactant and the active ingredient to form a mixture; melting the mixture; homogenizing the mixture to form a nanoemulsion; sonicating the homogenized nanoemulsion; and pouring the nanoemulsion into cold water to form the liquid nanoparticles. The lipid nanoparticles with active ingredient and the selected log P value has a prolong release property. In specific embodiment, the active ingredients are the chemical compound with the log P value selected from the range 0 to 4.0.