Provided is a portable battery soldering iron. An elastic piece, a spring ring, an indicator lamp and a soldering iron head are installed in a shell formed by connecting a front half shell body, a rear half shell body and a bottom plate, the elastic piece and the spring piece are connected with a battery, the indicator lamp is connected with the elastic piece and the spring ring, the soldering iron head is connected with a locking nut, a power switch is installed on the shell, a protective sleeve is connected with the top end of the shell, the protective sleeve is connected with the shell into a whole in a matched mode, and one end face of the protective sleeve is matched with the end face of the power switch. The structure is simple, a few of parts are used, the size is small, and the portable battery soldering iron is easy to manufacture and install and convenient to carry; the protective sleeve can prevent an operator from being scalded, other supporting parts do not need to be installed when the protective sleeve needs to be pulled out to serve as a soldering iron frame in actual operation, the situation that the battery soldering iron is started after being touched or impacted or after being mal-operated cannot occur due to the fact that the lower end face of the protective sleeve is tightly attached to the top face of the power switch in a matched mode, and factors and dangers capable of causing fires can be avoided and completely eliminated; the concave face on the protective sleeve is matched with an upper transverse limiting bar on the shell, connection firmness is improved, the battery soldering iron is convenient to use, and the protective sleeve is multifunctional, has a safety protection function and is made full use of.