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I have a series of coordinates for locations in Sichuan Province China that I need to convert so that I can use them in Google Earth. The coordinates are "1954 Beijing coordinates system" and show up as 3470081.60 36512300.88 with NO additional information other than elevation figures.

I ma pretty sure that the coordinate above corresponds with LAT 31.353305 LONG 108.131089 in WGS84 (Eastern Sichuan Province).

I'm struggling to understand what format the coordinates themselves are in - is it some type of modified MGRS? I'm assuming there are two steps I need to follow here, firstly to convert the coordinate system itself and then secondly to covert from the Chinese Datum to WGS84....right?

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The coordinate system might be EPSG:2412 Beijing 1954 / 3-degree Gauss-Kruger zone 36

with the Proj.4 definition

+proj=tmerc +lat_0=0 +lon_0=108 +k=1 +x_0=36500000 +y_0=0 +ellps=krass +towgs84=15.8,-154.4,-82.3,0,0,0,0 +units=m +no_defs

You can use that in GDAL ogr2ogr or cs2cs, or within the QGIS GUI to display the data, and convert to any other CRS.

For bulk converson with GDAL cs2cs, make sure to place the coordinates in longitude - latitude order in a textfile. Then run

cs2cs -f "%%.6f" +init=epsg:2412 +to +init=epsg:4326 infile >>outfile

For your reference point, I get 108.129622 31.352201 -63.598266. The last value is the difference between Beijing1954 and WGS84 ellipsoid height.

Both points are about 185m apart. If you worry about that, take a look at What causes the GPS offset/shift in China?

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