"小孩般说话" can be translated into English as "speak like a child" or "talk in a childlike manner".
"Speak like a child" is a straightforward and common expression, directly conveying the idea of speaking in a way that resembles how a child would.
"Talk in a childlike manner" is slightly more descriptive, emphasizing the manner or style of speaking as being similar to that of a child.
Both expressions are appropriate and can be used depending on the context and desired level of detail.