Shipment consolidation is widely applied by less-than-truckload carriers in stochastic demand environment．This paper studies collaboration among less-than-truckload carriers with stochastic demand under shipment consolidation policies，including time policy and quantity policy． Cost allocation problem of collaboration among less-than-truckload carriers is discussed under time policy and quantity policy，respectively． Cooperative game theory is applied to deriving cost allocations in the core． Furthermore，the choice of different shipment consolidation policies is discussed． The results show that customer service level is higher under time policy than that under quantity policy，while the total expected cost is less under quantity policy than that under time policy． It is also shown that collaboration among carriers not only reduces the cost of each carrier，but also enhances customer service level．