Попробуйте это:
/// <summary>
/// Retrieves the platform information from the process architecture.
/// </summary>
/// <param name="path"></param>
/// <returns></returns>
public static string GetPlatform(string path)
{
string result = "";
try
{
const int pePointerOffset = 60;
const int machineOffset = 4;
var data = new byte[4096];
using (Stream s = new FileStream(path, FileMode.Open, FileAccess.Read))
{
s.Read(data, 0, 4096);
}
// Dos header is 64 bytes, last element, long (4 bytes) is the address of
// the PE header
int peHeaderAddr = BitConverter.ToInt32(data, pePointerOffset);
int machineUint = BitConverter.ToUInt16(data, peHeaderAddr +
machineOffset);
result = ((MachineType) machineUint).ToString();
}
catch { }
return result;
}
public enum MachineType
{
Native = 0,
X86 = 0x014c,
Amd64 = 0x0200,
X64 = 0x8664
}