请问这句话有语法错误吗？谢谢……

语法有些许错误。其一，句子太长，到了后面就不通顺了。其二，句子说的是"main reason", 但是却没看清那一条才是真正的 "main reason".
我建议改一改句子，把它写成两句：The main reason for my confidence in this position lies in the fact that I am qualified for the job. Besides that, I believe that I have the right personality as a reporter.

错误，in 是介词后应跟名词或动名词，跟分句显然错误

The main reason for my confidence of this posistion is that not noly I have the qualifications for needing,but also I have the right personality for a reporter:我对这个职位自信的理由是，不仅拥有所需的证书，而且拥有作为个记者正确的品性。你要表达的是这个吗？

siewsian 的句子是对的，可用，但原因不准确....

1。main reason 应改成 main reasons，因为你讲了两个个理由。
2。不能用"do I“，因为这儿不能是一般疑问，可以改成"whether"
3。but also that I have the right personality.....

但我也建议分开写，可以表达得更明确。。。。

The main reason for my confidence in this position lies in the fact that I am qualified for the job. Besides, I believe that I have the right personality as a reporter.

no