The invention provides a construction method for earth pressure balance shield construction pressure launching in subway tunnel engineering. According to the method, a tunnel portal extending ring is matched with rubberized cord fabric, a folding pressure plate and a spring steel plate dual-sealing device to maintain pressure, and replacement is carried out on in-bin residue earth of a launching ring during trial boring launching. According to the method, pressure can be built quickly and normally to reach earth pressure balance tunneling requirements by replacing the in-bin residue earth of the launching ring when the launching ring excavates during the shield launching, water burst risk and sand burst risk generated by directly breaking a tunnel portal are avoided, the construction period is shortened and the construction cost is reduced. According to the shield tunnel construction pressure launching construction method, the risk increased by directly breaking the tunnel portal can be avoided, the leakproofness of the tunnel portal can be ensured, construction pressure excavation can be quickly realized, cost is saved, and the construction safety of the shield tunnel can be guaranteed.