可能是因为多部分上传时使用的AWS签名不正确。您可以确保使用multipart / upload签名版本，并按照以下代码示例执行AWS签名v4请求：

var AWS = require('aws-sdk');
var fs = require('fs');

var s3 = new AWS.S3();
var bucketName = 'YOUR_BUCKET_NAME_HERE';
var keyName = 'YOUR_KEY_NAME_HERE';
var filePath = 'YOUR_FILE_PATH_HERE';

var uploadID = null;

var startMultiPartUpload = function() {
  var params = {
    Bucket: bucketName,
    Key: keyName
  };

  s3.createMultipartUpload(params, function(err, data) {
    if (err) {
      console.log(err, err.stack);
    } else {
      uploadID = data.UploadId;
      console.log('Started MultiPart upload with ID:', uploadID);
      uploadParts();
    }
  });
};

var uploadParts = function() {
  var fileSize = fs.statSync(filePath).size;
  var parts = Math.ceil(fileSize / 5242880);

  var partParams = {
    Bucket: bucketName,
    Key: keyName,
    UploadId: uploadID,
    Body: '',
    PartNumber: 0
  };

  for (var i = 1; i <= parts; i++) {
    partParams.PartNumber = i;

    var start = (i - 1) * 5242880;
    var end = i * 5242880;
    if (end > fileSize) {
      end = fileSize;
    }

    partParams.Body = fs.createReadStream(filePath, {
      start: start,
      end: end - 1
    });

    s3.uploadPart(partParams, function(multiErr, mData) {
      if (multiErr) {
        console.log('Error uploading part:', multiErr);
        return;
      }
      console.log('Part uploaded:', mData);
    });
  }
};

startMultiPartUpload();

注意：该示例代码假定您已在计算机上配置AWS凭据。如果您尚未进行此操作，请改为使用AWS.config.loadFromPath（）或AWS.config.update