Dice2win is currently an extremely popular blockchain betting game on Ethereum. Known for its “provable fairness”, Dice2win currently has a bet of nearly one thousand Ethers (about 1.5 million RMB) per day, being the second largest Ethereum betting game after etheroll. However, our analysis found that all games in dice2win have fairness vulnerabilities, and the dealer can use these vulnerabilities to manipulate game results.