一封推荐信除了信头、发信日期、收信人姓名、称呼、信尾谦称、签名、推荐人姓名、职务等必需部分之外，正文内容说明应包括下列各项：
被推荐者的签名——为便于对方查询，被推荐者的签名仅写“MrWang”或“MissZhang”是不够的。用标准的汉语拼音或英文拼法都可以，但必须由被推荐者自己提供，且前后必须一致。
认识被推荐者的时间(Howlonghaveyouknowhim/her)——何时开始认识，或认识了多久。
认识程度(Howwelldoyouknowhim/her)——是偶尔见面还是关系密切，或仅教过一年还是担任其导师。
与被推荐人的关系(Relationship)——师生关系，上、下级领导关系等。
被推荐人的表现(Performance)——学习上、生活上、课堂上和课外活动上的表现。
结论意见——愿意推荐或不愿意推荐，无保留或有所保留的推荐、普通推荐或极力推荐，必须明确，当然极力推荐为最好。以上六项是任何一封推荐信所必须包括的，缺其中任意一项则都会失去函件应有的功能或会大大降低推荐的效果。
从法律上来说，推荐信(或称“工作证明信”)都是证据性的法律文件，是用来证明您的职业，以及与您的职业相关的工作经验的长短问题的。
一、推荐信的内容：
推荐信应包括哪些内容?这取决于推荐信的用途。我们在这里只从加拿大技术移民的需要这个角度，来讨论雇主推荐信应包括哪些内容。一封合格的雇主推荐信应该包含以下三部分的内容(缺一不可)：
(1)申请人的职业。
申请人的职业，必须在推荐信的第一段，明确说明。
申请人的职业的定义，是一个非常重要的问题。您的推荐信上所列的职业定义，应该是与您的申请表(IMM8)上第一页、第13格中所填写的职业定义，是完全一致的。事实上，您在填写移民申请表的时候，如何确定您的职业，应该是依据您的推荐信的内容。
中国人在写推荐信的时候，还有一个常犯的错误，那就是将职业(Occupation)和职务(Position)混淆使用。
(2)申请人在本单位所完成的具体项目或所参与的具体工作的内容。
您所参加的具体的项目或所参与的具体工作内容，必须一一具体列明。
(3)申请人在完成这些项目时，所使用的专业技能。
如果一封推荐信仅列明前面两项内容，即：申请人的职业的名称，以及申请人所参与的项目或工作内容，但没有说明他在工作中采用什么专业技能来实施该项目，或是完成该项工作，则您可能还是没有办法证明您的职业。
留学推荐信范文
Dear Colleagues：
As a teacher in Department of Biology, Nankai University, a leading university in China, I am very pleased to take this opportunity to recommend one of my favorite students to your PhD program.
In September, 2004, Miss Zhang was my students in General Biology, the first professional course they take in the field. She likes it very much. I teach her in an open and interactive manner, she is active and passionate about answering class questions.
Miss Zhang is bright, energetic and enthusiastic girl who loves speaking out her own ideas. She never escapes from those points of which she is skeptical. Apart from that, she often puts forward her ideas upon questions and exchanges all of her innovate ideas with me after class.
Upon ending of General Biology course, I asked my students to write an essay upon their understanding of biology. I discovered Miss Zhang’s essay was so impressive and persuasive; her careful essay comes from dozens of references to Biology literatures.
In essay Miss Zhang stretched out her creative thinking upon status quo of biological research and branches in the field of biology. All of this speaks to her creative and logical and scientific thinking capability.
I am gladly to say that Miss Zhang has a clear understanding about General Biology, that comprehension has been reflected fully in her essay. Therefore Miss Zhang got a full point for her essay in her class, and other students took it as model essay for granted.
I believe Miss Zhang’s industriousness, passion and dedication will make her an ideal candidate you are seeking for your program, so I highly recommend her without any hesitation to you. And I will greatly appreciate it if you could accept her into your program.
Sincerely yours,
Prof. ×××