The p-hydroxyphenylalanine test is commonly used in urine testing as one of the screening tools for malignant tumors. Early detection and early diagnosis are extremely important in the diagnosis and treatment of malignant tumors, of which tumor screening is one of the important means for early detection. Abnormal proliferation of malignant tumor cells causes abnormal increase in metabolism of amino acid-like substances and can be excreted from urine. It can be used as one of the methods for early cancer diagnosis. P-hydroxyphenylalanine is usually negative in normal urine and can be used as a broad-spectrum tumor marker. Compared with serum tumor markers, urine tests such as p-Hydroxyphenylalanine urine test are easy to obtain, non-invasive, fast response, can be detected at the early stage of tumorigenesis, and are relatively free of organ specificity, so they can be used for broad-spectrum screening and early diagnosis. P-hydroxyphenylalanine urine test has an important diagnostic value for malignant tumors, and it is recommended to go to the hospital in time when the index is abnormal.