The Studies on Pest Complex Were Conducted During Rabi Season at Research Farm of Janta Vedic College, Baraut (Baghpat) In Western Uttar Pradesh Revealed That 13 Species of Insect Pest Were Recorded to Infest the Mustard Crop. the Mustard Aphid (Lipaphis Erysimi Kalt.) Was Found As a Keypest Of Mustard Crop During the Study Period. Painted Bug (Bagarda Cruciferarum Kirk.) Was Found As a Minor Pest, First at Seeding Stage and Second at Harvesting State When the Crop Was In Maturing Stage. the Saw Fly (Athalia Lugens Proxima Klug.), Pea Leaf Miner (Chromatomyia Horticola Goureau.) and Flea Beetle (Phyllotreta Cruciferae Goeze) Were Also Found As a Minor Pest With Irregular Occurrence During The Study Period.