在我看来，性能、名称空间污染等都是次要的。问问自己什么是合乎逻辑的。该方法在逻辑上操作类型的实例，还是与类型本身相关?如果是后者，则将其设置为静态方法。只有当它与不受您控制的类型相关时，才将其移动到实用程序类中。

Sometimes there are methods which logically act on an instance but don't happen to use any of the instance's state yet. For instance, if you were building a file system and you'd got the concept of a directory, but you hadn't implemented it yet, you could write a property returning the kind of the file system object, and it would always be just "file" - but it's logically related to the instance, and so should be an instance method. This is also important if you want to make the method virtual - your particular implementation may need no state, but derived classes might. (For instance, asking a collection whether or not it's read-only - you may not have implemented a read-only form of that collection yet, but it's clearly a property of the collection itself, not the type.)

使方法静态意味着您可以从类外部调用该方法，而无需首先创建该类的实例。这在使用第三方供应商对象或附加组件时非常有用。想象一下，如果你在调用con. writeline()之前必须先创建一个Console对象“con”;

静态方法与实例方法 c#语言规范的静态成员和实例成员解释了这种差异。一般来说，静态方法可以提供比实例方法非常小的性能增强，但仅在某些极端情况下(有关详细信息，请参阅此回答)。

FxCop或代码分析中的CA1822规则规定:

在[将成员标记为静态]之后，编译器将向这些成员发出非虚拟调用站点，这将防止在 运行时，确保当前对象指针为 非空。这可以导致可测量的性能增益 性能敏感的代码。在某些情况下，访问失败 当前对象实例表示正确性问题。”

实用程序类 除非在设计中有意义，否则不应该将它们移到实用程序类中。如果静态方法与特定类型有关，就像ToRadians(双度)方法与表示角度的类有关一样，那么该方法作为该类型的静态成员存在是有意义的(注意，为了演示，这是一个复杂的示例)。

ReSharper不检查逻辑。它只检查方法是否使用实例成员。 如果方法是私有的，并且只被(可能只有一个)实例方法调用，这是一个让它成为实例方法的标志。

它有助于控制名称空间污染。

我希望您已经理解了静态方法和实例方法之间的区别。而且，答案可以有长有短。其他人已经给出了很长的答案。

我的简短回答是:是的，你可以像ReSharper建议的那样将它们转换为静态方法。这样做没有坏处。相反，通过将方法设置为静态，实际上是在保护该方法，这样就不会不必要地将任何实例成员插入该方法。通过这种方式，您可以实现OOP原则“最小化类和成员的可访问性”。

When ReSharper is suggesting that an instance method can be converted to a static one, it is actually telling you, "Why the .. this method is sitting in this class but it is not actually using any of its states?" So, it gives you food for thought. Then, it is you who can realize the need for moving that method to a static utility class or not. According to the SOLID principles, a class should have only one core responsibility. So, you can do a better cleanup of your classes in that way. Sometimes, you do need some helper methods even in your instance class. If that is the case, you may keep them within a #region helper.