According to the aggregating incremental effect in many industries by big data, the actualities that big data is lacked in the field of grain situation forecast in our country are analyzed.The big data of grain situation in grain depot is collected by establishment of cloud service platform shared among grain storage companies with the help of scalable EM probability clustering algorithm for massive data sets based on partial constraint information. Some opinions about grain storage security are proposed for providing better theory technical support to grain situation forecast in the futurity, and pointing out that the application of big data will become an important means and ways to improve food safety coefficient, so as to realize the goal of cost reduction and benefit increasing, at the same time looking forward to the future development trend.