Windshield wiper adapter and windshield wiper assembly

A windshield wiper adapter and windshield wiper assembly are disclosed. The windshield wiper adapter comprises a main body (21) and a flexible buckling device (23). A front end of the main body (21) has a notch (22) that is downwardly recessed. The notch (22) is used for snapping with a protrusion portion (11) of a windshield wiper arm (1) at an arbitrary angle. One end (231) of the flexible buckling device is connected to a surface of the main body (21) while another end (232) is upwardly extended toward an upper side of the main body (21). The flexible buckling device (23) is used for buckling a leaning side (121) of a through hole (12) of the windshield wiper arm (1). After the notch (22) is coupled to the protrusion portion (11), the windshield wiper arm (1) is rotated about a coupling portion therebetween, such that the flexible buckling device (23) is propped by the leaning side (121) of the through hole (12) to firstly perform a deformation process.