Objective To establish a prediction model for predicting the prognosis of synchronous brain metastasis in newly diagnosed colorectal cancer (SBCRC). Methods The clinicopathological and treatment data of SBCRC patients from 2010 to 2016 in SEER database were retrospectively analyzed. Independent prognostic factors were identified using multivariate Cox proportional hazard model. Then R software was used to establish the nomogram prediction model, and verify the model. Results Univariate analysis showed that age, tumor location, carcinoembryonic antigen (CEA)，radiotherapy, chemotherapy, liver metastasis, lung metastasis and bone metastasis were prognostic risk factors of SBCRC patients (all P<0.05). But the degree of tissue differentiation, race, gender, T stage and N stage were not correlated with the prognosis of SBCRC patients (all P>0.05). Multivariate analysis showed that age, chemotherapy, operation, bone metastasis and positive CEA were independent prognostic factors of SBCRC patients (all P<005). The Cindex of the prognosis model of the nomogram was 0749 (95% CI:07260772), and the areas under the ROC curves were 0823 and 0788, respectively. Meanwhile, the calibration curve showed that the predicted 6month and 1year survival rate by the nomogram was in good agreement with the observed 6month and 1year survival rate. Conclusion The nomogram based on the age, CEA, bone metastases, operation and chemotherapy were tested to have an effective predictive prognosis power in SBCRC patients.