事情是$scope.inventory.condition必须是$scope.conditions数组元素，并且两个对象只有当它们是同一个对象时才相等。所以你不能只设置$scope.inventory.condition = {"name":"Used","id":102};: event 虽然{"name":"Used","id":102}看起来像数组的第二个值，但实际上它们并不相等，所以 Angular 不会将它设置为默认值。

您需要像这样设置模型值：

$scope.conditions = [
    {"name":"New","id":101},
    {"name":"Used","id":102},
    {"name":"Like new","id":103},
    {"name":"Not Working","id":104}
];
$scope.inventory.condition = $scope.conditions[1];