Abstract: A method of photoresist strip includes providing a semiconductor substrate and performing an immerse step and a strip step, wherein the semiconductor substrate comprises a base, a bonding pad, a protective layer, an under bump metallurgy layer, a patterned photoresist layer and a bump. The patterned photoresist layer covers the under bump metallurgy layer and a lateral surface of the bump, wherein a first connection interface is formed between the patterned photoresist layer and the lateral surface of the bump, and a second connection interface is formed between the patterned photoresist layer and the under bump metallurgy layer. In the immerse step, the patterned photoresist layer contacts with a chemical solution which degrades the bond strength of the first connection interface. Therefore, in the strip step, the semiconductor substrate is scoured by a flow with appropriate force of impact, which strips the patterned photoresist layer from the base.