Question

Why draupadi did not marry karna?

Answer 1

because at that time karna was not a king.

Answer 2

In one version of Mahabharat, King Drupad, who was defeated by Arjuna earlier was so impressed by Arjuna, that he wanted to give his daughter Draupadi in marriage to him. He used to praise and boast his might too often, to the point that she started to have a liking towards Arjuna. The archery feat in the swayamvar was intended intentionally to lure in Arjuna. Drupad was under the belief that Arjuna alone can win the swayamvar.

In this scenario, when it was Karna's turn, Draupadi, did not want to marry him as she wanted to marry Arjuna. So, in her haste to avoid Karna, she proclaimed that she will not marry a person from the lower caste.