Abstract: The present invention discloses a novel class of monoacylglycerol lipase (MAGL) small molecule inhibitors, as well as pharmaceutical compositions, preparation methods, and uses thereof. The MAGL small molecule inhibitors are represented by formula (I), with specific substituents and definitions as described in the specification. The disclosed MAGL small molecule inhibitors exhibit excellent MAGL enzyme inhibitory activity. The invention includes these compounds or their pharmaceutical compositions for the treatment and/or prevention of MAGL-related conditions such as multiple sclerosis, Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, traumatic brain injury, neurotoxicity, stroke, epilepsy, anxiety, migraine, depression, hepatocellular carcinoma, colorectal cancer lesions, ovarian cancer, neuropathic pain, chemotherapy-induced neuropathy, acute pain, chronic pain, and/or pain-associated spasticity.