How do you say in french I was surprised by that Ça m a surpris?

You're close, but there's a small grammatical adjustment needed!

The correct way to say "I was surprised by that" in French is:

"Ça m'a surpris."

You were right about "ça" and "surpris," but you need to include the "m'" which is the contraction of "me" in this context.

Let me know if you have any other French phrases you'd like to translate!