aim at 是主动,表打算、准备.
be aimed at 是被动,表被打算.
非谓语做放在句首如果后面的主语与动词是主动关系,用aiming at.例：Aiming at improving his grades,his parents sent him to the school.这里父母作为主语,是主动状态,想要送他去学校来提高成绩.父母（主语）和打算（谓语动词）之间是主动关系.
如果主语和谓语动词是被动关系,就用be aimed at.例：The picture,aimed at show off their love, was put in the dining room.这张被用来炫耀他们的甜蜜的照片被摆在了餐厅里.
主要是看主语与谓语动词的主被动关系来选择~