The invention belongs to the technical field of synthetic fiber production, in particular relates to a high-strength ultra-low thermal contraction nylon 66 fiber and a production method thereof. The nylon 66 fiber is characterized in that the strength is 8.0-9.5g/d, the elongation at break is 18-24%, the free hot air shrinkage rate at 180 DEG is 2.0-4.0%, the linear density is 150-1050D, and the monofilament linear density is 4.0-8.0D. The high-strength ultra-low thermal contraction nylon 66 fiber has advanced performance and can meet higher industrial use requirements; the production adopts a one-step method, thereby achieving high-speed, continuous and stable production with high production efficiency and high yield and uniform and stable performance of products in different batches; and the production method has short technological processes and obvious economic benefit.