Objective To explore the medication rules of TCM ointment in the treatment of functional constipation.Methods From 2016 to 2018,137 prescriptions for functional constipation were collected from Professor Cai Gan’s ointment outpatient department.The application frequency of commonly used herbal drugs was calculated and SPSS modeler 18.0 Apriori algorithm was used to analyze the usage of different drug combinations in the treatment of functional constipation.Results The most commonly used five Chinese herbs were:Radix Aucklandiae,Raw licorice,Poria cocos,Pseudostellaria principis,Orange peel;the most commonly used five groups of herbal medicines were Pinellia and Orange peel,Amomum villosum and Radix Aucklandiae,Amomum kravanh and Radix Aucklandiae,Amomum kravanh and Amomum villosu,Raw atractylodes and Licorice.Conclusion The ointment prescription in treating functional constipation attaches great importance to the care of the spleen and the stomach,strengthening spleen and helping transportation as the main method,and compatible with the Methods of moisturizing bowel,clearing heat and removing dampness,nourishing yin and fluid,promoting blood circulation and removing blood stasis,dissipating phlegm and removing stagnation,tonifying kidney and purgation.