Excel.Application myExcel = new Excel.Application();
object missing = System.Reflection.Missing.Value;
myExcel.Application.Workbooks.Open(this.txtFile.Text, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing); //this.txtFile.Text为Excel文件的全路径
Excel.Workbook myBook = myExcel.Workbooks[1];

//获取第一个Sheet
Excel.Worksheet sheet = (Excel.Worksheet)myBook.Sheets[1];　
string sheetName = sheet.Name; //Sheet名

//获取全部Sheet名

public static StringCollection ExcelSheetName(string filepath)
{
StringCollection names = new StringCollection();
string strConn;
strConn = "Provider=Microsoft.Ace.OLEDB.12.0;Data Source=" + filepath + ";Extended Properties=‘Excel 12.0;HDR=Yes;IMEX=2‘";
OleDbConnection conn = new OleDbConnection(strConn);
conn.Open();
DataTable sheetNames = conn.GetOleDbSchemaTable
(System.Data.OleDb.OleDbSchemaGuid.Tables, new object[] { null, null, null, "TABLE" });
conn.Close();

foreach (DataRow dr in sheetNames.Rows)
{
names.Add(dr[2].ToString());
}
return names;
}

备注：操作完后要关闭：

myBook.Close(Type.Missing,Type.Missing,Type.Missing);
myExcel.Quit();