A zoom lens having a high zoom ratio and also a small size is proposed. The zoom lens has a front group of lenses and a rear group of lenses. The front group of lenses has a first lens, a second lens, and a third lens. The first lens is a meniscus negative lens. The second lens is a biconcave lens negative lens. The third lens is a positive lens. The rear group of lenses has a fourth lens, a fifth lens, a sixth lens, and a seventh lens. The fourth lens is a positive lens. The fifth lens is a biconvex lens. The sixth lens is a meniscus negative lens. The seventh lens is a meniscus negative lens. The fourth and seventh lenses are aspheric lenses made of plastic material. The proposed zoom lens can meet the requirement of miniaturized size and also maintain the image quality.