The main purpose of this methodological study was to develop an assessment tool and intervention protocol for child and family with childhood cancer at early diagnosis stage. The assessment tool and intervention protocol was developed by extensive literature review and consultation with experts. Review of nine domestic and sixty-six international journal articles were done to identify stress, interventions, coping strategies and adjustment of children with cancer and their family. Results were as follows; First, assessment at the early diagnosis stage need to include information on patient, family, and patient/family attitude toward diagnosis and treatment. Second, intervention protocol for children with cancer includes control physical symptoms, manage the side effects of chemotherapy and diagnostic or therapeutic procedures, control emotional responses, provide support and information, assist decision-making and adjust to environment. Third, intervention protocol for family includes controlling emotional responses, provision of informations, inducing family support to patient, improving family cohesion, supporting siblings and supporting spiritual growth. In conclusion, the early diagnosis stage in cancer treatment is important for child and family since this stage greatly affects the overall adjustment of child and family to live with cancer. Therefore, pediatric nurses need to be sensitive to the need of patient/family and systematically manage their needs at this stage.