LaTeX文档插入png图片

Use the graphicx package with the following command in the preamble:

\usepackage{graphicx}

Yes, there are others but this is the best and most widely used.
Insert the figure: using the figure environment as follows:

\begin{figure}[htb]

\center{\includegraphics[width=5cm]  {pic-name.png}}

\caption{\label{1} My figure.  An example of a cool figure}

\end{figure}