Bois de Boulogne and Bois de Vincennes are the 1st and 3rd biggest urban parc in Europe.
There is also Parc de Monceau, Parc des Buttes Chaumont, Parc de Monsouri, Parc de Belleville, Parc du Luxembourg, Parc de Bercy, Parc Andre Citroen Champs de Mars... in the inner city.
There is also park outside the inner city : parc de Sceaux (very beautiful), parc de Bagnolet.....
Paris has also urban forest (Bois de boulogne and Bois de Vincennes are artificial, these were created) : Foret de Meudon, this natural forest is completly surrounded by the urban area.
When the inner city is not very green the outer city (Called inner suburbs because are not officially in Paris proper due at artificially frozen city limit
) and the suburbs have many green space.