An experiment was carried out in matured Khasi mandarin plot at the Barekuri village of Tinsukia in Assam to standardize the nutrient requirement in Khasi mandarin and its effect on yield, quality and nutrient content of Khasi mandarin and soil status of Khasi mandarin plot. The experiment has been conducted for six years. The experiment was laid out with 5 m × 5 m spacing along with 4 treatments, 5 replication and designed with RBD. Among the four treatments, T2 treatments were found better for maximize yield and fruit quality of matured Khasi mandarin. Treatment (T2) containing fertilizer application of N, P2O5 and K2O at 0:0:0 per cent of RDF during January- February, 30:40:10 per cent of RDF during March- April, 30:35:10 per cent of RDF during May- June 20:25:30 per cent of RDF during July- August, 10:0:25 per cent of RDF during September- October and 10:0:25 per cent of per cent of RDF during November-December was found better in terms of yield, quality of Khasi mandarin and fertility status of soil. Regarding, fruit qualities, higher juice content (47.72%), maximum TSS (11.20°Brix) and maximum number of fruits per tree (342) were observed in above mentioned treatment (T2). Maximum soil nutrient status and NPK content on leaf were recorded under the same T2 treatment. The maximum B: C ratio (2.20) was found in the same T2 treatment.