"构成的化学元素" can be translated as "the constituent chemical elements" or "the chemical elements that constitute [something]" (where "[something]" is replaced by the specific substance or material being referred to).
If you're referring to the elements that make up a particular compound or material, you might say something like:
"The constituent chemical elements of water are hydrogen and oxygen."
（水的构成化学元素是氢和氧。）
Or more simply, when the context is clear:
"Water is constituted by hydrogen and oxygen." （水由氢和氧构成。）虽然此句未直接使用 "chemical elements"，但意思明确，若需强调元素，可改为 "Water is constituted by the chemical elements hydrogen and oxygen."