In this paper， the grammatical devices of cohesion are analyzed. The chosen text PUZZLES IN GEOGRAPHY is taken from New Senior English for China Student’s Book 5. It clarifies how four countries formed the UK and gives a brief introduction of England and London. （refer to Appendix for full text）.
　　Introduced in the course， cohesion is complementary to coherence andrefers to the linking relationships that are explicitlyexpressed in the surface structure of the text. The devices of cohesion are reference， substitution & ellipsis， conjunction， theme-rheme and tense & aspect.
　　According to the different directions of arrows above， it’s easy to conclude that there are anaphoric references（backward-pointing） and cataphoric references（forward-pointing）， with the former making up the majority in this text. As an indicator of how a discourse is constructed， anaphoric reference is achieved through pronouns referring back to the items previously appeared in the text， which is beneficial to achieve the conciseness of a text. Besides， three types of grammatical reference can be found.For example， there are many pronominal references by personal pronouns such as it and they.
　　Secondly， it is about the substitution & ellipsis. With an item replaced by something else，substitution is helpful to make sentences more concise. There is an examplesin the sixth line of the fourth paragraph.“two” means “two football teams”， avoiding the repetition of such a long phrase.
　　Thirdly， it is about the conjunctions. In the text， these conjunctions are easily found，“For example”“First， next， finally”， “However， so， but， although”， etc. As adverbial connectors， these conjunctions have the function of binding ideas， clauses and segments of discourse into cohesive sequences. “Conjunctions are important cohesive device for discourse construction.”（Halliday&Hasan，，1976）.AccordingtoHalliday and Hasan，conjunctions are rather  different from other cohesive devices.A conjunction specifies the connection between whatisfollowing and what has gone before. In the text，“for example” shows that the author prepares to prove and explain more about the fact about four countries having different institutions with the use of examples.“however， so， but， although” denotes the logic relationships between sentences and paragraphs in this text， take “however” for example， it’s used to show that the southern Ireland’s unwillingness contrast to other countries. “First， next， finally” shows the time order of four countries making up the United Kingdom.