地址：https://github.com/Leaflet/Leaflet/issues/6101，
看這個就行，按照這個說的做：

image.png

/* 
 * Workaround for 1px lines appearing in some browsers due to fractional transforms
 * and resulting anti-aliasing.
 * https://github.com/Leaflet/Leaflet/issues/3575
 */
(function(){
    var originalInitTile = L.GridLayer.prototype._initTile
    L.GridLayer.include({
        _initTile: function (tile) {
            originalInitTile.call(this, tile);

            var tileSize = this.getTileSize();

            tile.style.width = tileSize.x + 1 + 'px';
            tile.style.height = tileSize.y + 1 + 'px';
        }
    });
})()