The present invention relates to an inflatable device for producing hydrogen, in particular to an anti-scalding, safe, low-pressure, environment-friendly hydrogen machine and gas preparation method for inflating toy balloons and advertising balloons. The hydrogen machine of the present invention includes: a liquid inlet , reactor, purifier, check valve, gas-water mixing cooler, gas-water separator and sewage storage tank. During the preparation process, the reaction liquid is injected into the reactor through the liquid inlet, and the occurrence of the reaction is controlled through the liquid inlet valve. And stop, purify and preliminarily cool the foam-containing crude hydrogen product prepared by the reactor through the purifier, further cool the pure hydrogen through the gas-water mixing cooler, and finally use the gas-water separator to obtain hydrogen and cooling water Separation to achieve the purpose of aeration. The hydrogen produced by the invented hydrogen machine has high purity and good aeration effect. At the same time, the reaction residual liquid can be collected and reused, which greatly reduces energy consumption and material consumption, making the entire preparation process economical, reasonable, environmentally friendly and safe.