The stringent requirements of ultra-reliable and low latency communication (URLLC) services is the most challenging feature of fifth generation systems. The design and optimization of efficient short length codes is essential for URLLC. This letter investigates a novel weight coefficient progressive edge-growth (WCPEG) algorithm to construct ultra-reliable analog fountain codes (AFCs) in the short length regime. Our WCPEG AFC can approach the normal approximation benchmark by eliminating the small girth cycles in the encoding Tanner graph. We first analyze the properties of short length AFC, and then present the comprehensive description and theoretical identification of the WCPEG AFC algorithm. Simulation results demonstrate the superior performance of WCPEG AFC in the short length regime.