TO
＊＊＊＊＊＊＊＊＊
ATTENTION: ＊＊＊＊＊＊
A FORMAL VISA INVITATION
Dear Sir or Madam:
We are very pleased to invite Mr. ＊＊＊ come to our factory for visiting and business negotiation. The business trip will start from 18th April 20xx年 例如：Friday, March 16, 20xx年结束之际"，用at the end of this fiscal year] at the (地点- 例如：Marriot Hotel 这个美、加一家较有名气得连锁饭店，只是举例因为我不是很清楚国内得情况). If your schedule would allow, we will have transportation ready for you at (时间）. [这句话的意思是"如果您的行程许可，我们将在（时间）为您备好车"。"如果您的行程许可"只是客套话，但应该说，表示礼貌。如果被邀请方没有车，那您应该提供交通工具。] We would be delighted if you will attend.
RSVP: [意思是请回复，邀请函上常见的字头语](您的联络方式：要提供电子邮箱和电话)
Sincerely,
(签名)
Managing Director of ABC China
以上是正规的邀请函格式。我加了一些注解，希望有帮助。我是以公司整体名义写的，如果您想以个人名发出邀请就把人称换一下就好了。下面我完整的写一份邀请函给您做例子。
Dear <Mr. Peterson>:
You have been very supportive to [us](me) in the past year of operation and [we are](I am) extremely grateful for all you've done. To show [our](my) appreciation, [we](I) would like to invite you to [dinner](a dinner party) on Friday, March 16, 2007 at the <Marriot Hotel>. If your schedule would allow, we will have transportation ready for you at <6:30 PM>. [We](I) would be delighted if you will attend.
RSVP: <abcchina@yahoo.com> or <4038569957>
Sincerely,
<您的签名>
Managing Director of ABC China
如果以公司名义，用[]里的第一人称复数。要是以个人名义，用（）里的第一人称单数。<>里面是您需要填的资料。
PS：感觉就是一般英文信的写法。
第二种：
PS：相当正式的官方邀请函。
第三种：
LETTER OF INVITATION
Dear Sirs/Madam:
We hereby sincerely invite you and your company representatives to visit our booth at The Continental Exhibition Center from April 15th to 20th 2006.
We're one of the manufacturers specialized in sanitaryware, concluding one & two piece toilet, wash basin, cabinet basin, pedestal basin, bidet, urinal, counter basin , decorated ceramics and so on. Our new models offer superb design and their new features give them distinct advantages over similar products from other manufacturers.
It would be a great pleasure to meet you at the exhibition.We expect to establish long-term business relations with your company in future.
Exhibition Center : The Continental Exhibition Center
Booth Number : G-K105 G-K-106
Date : Apr 15th to 20th 2006
Best Regards,
Mr.Su Jia Jian
General Manager
PS:本人认为，这种很有可能是对的。
第四种：
A FORMAL VISA INVITATION格式
公司抬头
TO
＊＊＊＊＊＊＊＊＊
ATTENTION: ＊＊＊＊＊＊
A FORMAL VISA INVITATION
Dear Sir or Madam:
We are very pleased to invite Mr. ＊＊＊ come to our factory for visiting and business negotiation. The business trip will start from 18th April 2005 . And because the long business co-operation in future between ＊＊对方公司名 and us, they will come to China for many times.
Please note, however, that we don’t assume any legal or financial responsibility whatever regarding the presence of ****** in China. All expenses of ＊＊＊＊＊’Ｓjourney to/from China, their stay in China as well as health insurance will be borne by their employers.
We send you our kindest regards and best wishes for a pleasant trip.
Yours sincerely,
signature
General Manager
PS:没太看明白，是怎么回事